| SURNAME | GIVEN NAME | CD # | NEWSPAPER | DATE | PAGE | SUBJECT | NOTES | MP |
| OAKS | Dr. | 13 | Parker City Daily | 02 Mar 1876 | 3 | Death Notice | Titusville | |
| OALNER | John T. | 7 | The Democratic Herald | 23 Nov 1859 | 3 | Sheriff's Sales | Summit Twp | |
| OATEN | Ralph | 16 | The Democratic Herald | 04 Nov 1898 | 6 | Arrested | X | |
| OATMAN | L. H. | 14 | Connoquenessing Valley News | 17 Jul 1879 | 3 | Advertisement | Rochester, Beaver County | X |
| O'BALL | John | 11 | American Citizen | 17 Jan 1872 | 3 | Death Notice | ||
| OBREEN | A. J. H. | 14 | Parker City Daily | 13 Jul 1876 | 3 | Guest of Railroad | Netherlands | |
| O'BRIAN | A. | 11 | Butler County Citizen | 04 Sep 1872 | 2 | Court | ||
| O'BRIAN | A. | 11 | Butler County Citizen | 11 Sep 1872 | 3 | Court | ||
| O'BRIAN | Anthony | 9 | American Citizen | 26 May 1869 | 2 | Restaurant License | Fairview | |
| O'BRIAN | Frank | 11 | Butler County Citizen | 04 Sep 1872 | 2 | Court | ||
| O'BRIAN | Frank | 11 | Butler County Citizen | 11 Sep 1872 | 3 | Court | ||
| O'BRIAN | James | 13 | Parker City Daily | 04 Mar 1876 | 3 | Tardy | Karns City | |
| O'BRIAN | N. | 11 | Butler County Citizen | 02 Sep 1874 | 2 | Court | ||
| O'BRIAN | T. J. | 13 | Parker City Daily | 08 Jan 1876 | 3 | Letter | Petrolia | |
| O'BRIEN | A. | 11 | Butler County Citizen | 10 Sep 1873 | 3 | Politics | ||
| O'BRIEN | A. | 11 | Zieglers Democratic Herald | 12 Feb 1874 | 4 | Death Notice | ||
| O'BRIEN | Abner | 16 | The Democratic Herald | 24 Feb 1898 | 1 | Marriage | ||
| O'BRIEN | Anthony | 9 | Democratic Herald | 03 Jun 1868 | 6 | License Restaurant | Fairview | |
| O'BRIEN | Anthony | 9 | Democratic Herald | 02 Jun 1869 | 4 | Restaurant License | Fairview | X |
| O'BRIEN | Anthony | 9 | Democratic Herald | 31 Mar 1869 | 2 | Tavern License | Fairview | |
| O'BRIEN | Bernard | 8 | The Union Herald | 12 Mar 1862 | 3 | Sheriff's Sales | Fairview Twp | |
| O'BRIEN | Bernard | 16 | The Democratic Herald | 06 May 1898 | 5 | Will | Donegal Twp | |
| O'BRIEN | Daniel | 16 | The Democratic Herald | 18 Feb 1898 | 1 | New Employment | ||
| O'BRIEN | J. J. | 13 | Parker City Daily | 22 Mar 1876 | 3 | Restaurant | ||
| O'BRIEN | J. J. | 14 | Parker City Daily | 03 Jun 1876 | 3 | Boarding House | X | |
| O'BRIEN | James | 14 | Parker City Daily | 13 Jul 1876 | 3 | Escaped from Jail | Meadville | |
| O'BRIEN | James | 16 | The Democratic Herald | 06 May 1898 | 5 | Will | Donegal Twp | |
| O'BRIEN | John | 16 | The Democratic Herald | 06 May 1898 | 5 | Will | Donegal Twp | |
| O'BRIEN | Louis | 13 | Parker City Daily | 08 Jan 1876 | 3 | Letter | Petrolia | |
| O'BRIEN | Mannus | 16 | The Democratic Herald | 06 May 1898 | 5 | Will | Donegal Twp | |
| O'BRIEN | Mrs. T. J. | 14 | Parker City Daily | 16 Jun 1876 | 3 | Donation | Millerstown | |
| O'BRIEN | Terence | 13 | Parker City Daily | 25 Oct 1875 | 3 | Candidate | Millerstown | |
| O'BRIEN | Terry | 14 | Parker City Daily | 29 Apr 1876 | 3 | Made Improvements | ||
| O'BRIEN | Tery | 14 | Parker City Daily | 20 Jul 1876 | 3 | Famous Beer Man | ||
| O'BRIEN | Thos. | 1 | The Butler Centinel | 10 Jul 1821 | 3 | List of Letters | Butler | X |
| O'BRIEN | W. H. | 16 | The Democratic Herald | 14 Jan 1898 | 5 | Plumber | ||
| O'BRIEN | William | 16 | The Democratic Herald | 06 May 1898 | 5 | Will | Donegal Twp | |
| OCHILTREE | Tom | 15 | Connoquenessing Valley News | 31 Jul 1884 | 3 | Returned Home | ||
| OCHTON | John | 2 | The Repository | 10 Oct 1835 | 3 | Unclaimed Letter | Slippery Rock | |
| O'CONER | Thomas | 1 | The Butler Centinel | 26 Jan 1822 | 2 | Public Notice | Cranberry Twp | X |
| O'CONLEY | Patrick | 11 | Butler County Citizen | 03 Apr 1872 | 2 | Notice | ||
| O'CONLEY | Patrick | 11 | Butler County Citizen | 10 Apr 1872 | 3 | Court | ||
| O'CONLEY | Patrick | 11 | Butler County Citizen | 17 Apr 1872 | 3 | Court | ||
| O'CONLEY | Patrick | 11 | Butler County Citizen | 24 Apr 1872 | 3 | Court | ||
| O'CONLEY | Patrick | 11 | Butler County Citizen | 01 May 1872 | 3 | Court | ||
| O'CONLEY | Patrick | 11 | Butler County Citizen | 08 May 1872 | 3 | Court | ||
| O'CONLEY | Patrick | 11 | Butler County Citizen | 15 May 1872 | 4 | Court | ||
| O'CONLEY | Patrick | 11 | Butler County Citizen | 29 May 1872 | 4 | Court | ||
| O'CONLEY | Patrick | 11 | Butler County Citizen | 05 Jun 1872 | 4 | Court | ||
| O'CONNELL | Dan | 14 | Parker City Daily | 13 May 1876 | 3 | Lease | ||
| O'CONNER | D. | 16 | The Democratic Herald | 07 Jan 1896 | 1 | Officers Installed | ||
| O'CONNER | John | 5 | Butler Intelligencer | 27 Feb 1841 | 2 | Sheriff Sale | Evansburg | |
| O'CONNER | John | 6 | Democratic Herald | 07 Mar 1855 | 1 | Sheriff's Sale | Slippery Rock Township | |
| O'CONNER | John | 13 | Parker City Daily | 01 Feb 1876 | 3 | Merchant | X | |
| O'CONNER | Michael | 16 | The Democratic Herald | 25 Mar 1898 | 1 | Obituary | ||
| O'CONNOR | Charles | 14 | Parker City Daily | 03 Jul 1876 | 3 | Address | ||
| O'CONNOR | John | 2 | Butler Sentinel | 03 Feb 1827 | 4 | Tax Collector | Cranberry Twp. | |
| O'CONNOR | John | 3 | Butler Repository | 28 Jan 1837 | 3 | Tax Collector | Cranberry Twp. | |
| O'CONNOR | John | 11 | Butler County Citizen | 02 Sep 1874 | 2 | Court | ||
| O'CONNOR | Lawrence | 11 | Butler County Citizen | 02 Sep 1874 | 2 | Court | ||
| O'CONNOR | Miss Mabel | 16 | The Democratic Herald | 04 Mar 1898 | 4 | Attended Social | Hilliard | |
| O'CONNOR | Miss Madge | 16 | The Democratic Herald | 11 Mar 1898 | 9 | Out of Town | Hilliard | |
| O'CONNOR | Miss Maudeline | 16 | The Democratic Herald | 17 Jun 1898 | 5 | Visiting | ||
| O'CONNOR | Patrick | 8 | The Butler Union Herald | 18 May 1864 | 3 | Treasurer's Sales | Venango Twp | |
| OCT 14, 1852 ISSUE NOT PUBLISHED | 6 | Democratic Herald | 20 Oct 1852 | 2 | ||||
| OCTOBER TERM | First Week | 9 | Democratic Herald | 22 Sep 1869 | 3 | Trial List | ||
| OCTOBER TERM | 9 | American Citizen | 08 Sep 1869 | 3 | Trial List | |||
| ODA | Peter | 11 | The Democratic Herald | 29 Mar 1871 | 2 | Official | ||
| O'DAY | Dan. | 13 | Parker City Daily | 15 Sep 1875 | 3 | Superintendent | ||
| O'DAY | P. | 13 | Parker City Daily | 11 Oct 1875 | 3 | Rules & Regulations | ||
| ODELL | Vermira | 6 | Democratic Herald | 26 Jul 1851 | 3 | Marriage | Callensburgh, Clarion C, | |
| O'DENNEL | Arthur | 7 | The Democratic Herald | 23 Jul 1856 | 3 | Fair Committee | Clearfield Twp | X |
| ODENWEILLER | John | 14 | Parker City Daily | 26 Aug 1876 | 3 | Erecting House | ||
| ODGEN | Rev. Ephraim | 8 | The Butler Union Herald | 24 Feb 1864 | 3 | Marriage | ||
| ODGEN | William R. | 11 | Zieglers Democratic Herald | 12 Feb 1874 | 3 | Court | ||
| O'DONALD | Daniel | 4 | Butler Intelligencer | 06 Jun 1840 | 3 | Sheriff's Sales | Clearfield Township | |
| O'DONALD, SR. | Connel | 1 | The Butler Centinel | 26 Jan 1822 | 1 | Public Notice | Donegal Twp. | X |
| O'DONALL | Patrick | 11 | Butler County Citizen | 10 Apr 1872 | 3 | Court | ||
| O'DONALL | Patrick | 11 | Butler County Citizen | 17 Apr 1872 | 3 | Court | ||
| O'DONALL | Patrick | 11 | Butler County Citizen | 24 Apr 1872 | 3 | Court | ||
| O'DONALL | Patrick | 11 | Butler County Citizen | 01 May 1872 | 3 | Court | ||
| O'DONALL | Patrick | 11 | Butler County Citizen | 08 May 1872 | 3 | Court | ||
| O'DONALL | Patrick | 11 | Butler County Citizen | 15 May 1872 | 4 | Court | ||
| O'DONALL | Patrick | 11 | Butler County Citizen | 29 May 1872 | 4 | Court | ||
| O'DONALL | Patrick | 11 | Butler County Citizen | 05 Jun 1872 | 4 | Court | ||
| O'DONNALL | Jack | 1 | The Butler Centinel | 03 Apr 1821 | 3 | List of Letters | Butler | |
| O'DONNEL | 5th Sgt. Joseph H. | 16 | The Democratic Herald | 29 Apr 1898 | 1 | Off to War | ||
| O'DONNEL | Annie Lillian | 9 | Democratic Herald | 30 Sep 1868 | 3 | Death | Clarion County | |
| O'DONNEL | Arthur | 4 | Butler Intelligencer | 07 Mar 1840 | 5 | Public Notice | Hannahstown | X |
| O'DONNEL | B. J. | 11 | The Democratic Herald | 10 May 1871 | 3 | Notice | Miss | |
| O'DONNEL | Charle | 9 | Democratic Herald | 30 Sep 1868 | 3 | Death | Clarion County | |
| O'DONNEL | Connel | 2 | Butler Sentinel | 18 Feb 1826 | 3 | Death Notice | Donegall Twp. | |
| O'DONNEL | Dennis | 6 | Democratic Herald | 10 Mar 1852 | 3 | Administrator's Notice | Donegal Township | |
| O'DONNEL | Fran C. | 8 | The Butler Union | 22 Jul 1863 | 3 | Drafted | Oakland Twp | |
| O'DONNEL | Jacob | 5 | Butler Intelligencer | 24 Jun 1841 | 2 | Estate Sale | Donegal | |
| O'DONNEL | John | 1 | The Butler Sentinel | 30 Nov 1822 | 3 | Marriage | Donegal Twp. | |
| O'DONNEL | John | 2 | The Repository | 10 Oct 1835 | 5 | Stray Mare | Donegal Twp. | |
| O'DONNEL | Mary | 4 | Butler Intelligencer | 08 Feb 1840 | 3 | Sheriff's Sale | Donegal Township | |
| O'DONNEL | Mary | 9 | Democratic Herald | 30 Sep 1868 | 3 | Death | Clarion County | |
| O'DONNEL | Miss Sarah | 1 | The Butler Sentinel | 05 Feb 1825 | 3 | Marriage | Clearfield Twp. | |
| O'DONNEL | Neal | 4 | Butler Intelligencer | 08 Feb 1840 | 3 | Sheriff's Sale | Donegal Township | |
| ODONNELL | Connell | 9 | Democratic Herald | 14 Aug 1867 | 4 | Estate | Donegal | X |
| ODONNELL | John | 5 | Butler Intelligencer | 16 Oct 1841 | 3 | Unclaimed Letters | ||
| ODONNELL | John | 9 | Democratic Herald | 14 Aug 1867 | 4 | Estate | Donegal | |
| O'DONNELL | Agnes | 16 | The Democratic Herald | 10 Jun 1898 | 4 | Week in Court | Zelienople | |
| O'DONNELL | Arthur | 2 | Butler Sentinel | 10 Jan 1829 | 2 | Letter | ||
| O'DONNELL | Arthur | 8 | The Union Herald | 30 Jul 1862 | 3 | Soldiers | Clearfield Twp. | X |
| O'DONNELL | Charles | 1 | The Butler Sentinel | 26 Nov 1825 | 3 | Death Notice | Clearfield Twp. | |
| O'DONNELL | Con. | 13 | Parker City Daily | 24 Jan 1876 | 3 | Recuperating | Foxburg | X |
| O'DONNELL | Connel | 9 | Union Herald | 15 May 1867 | 2 | Estate | Donegal | |
| O'DONNELL | Connel | 9 | Union Herald | 15 May 1867 | 3 | Death | Donegal | |
| O'DONNELL | Connell | 4 | Butler Intelligencer | 04 Sep 1840 | 1 | Sheriff's Sales | Donegal Township | |
| O'DONNELL | Cpl M. | 8 | The Butler Union | 17 Sep 1861 | 2 | Company Roll | ||
| O'DONNELL | D | 13 | Parker City Daily | 03 Nov 1875 | 3 | Local Election | ||
| O'DONNELL | Daniel | 14 | The Butler County Citizen | 19 Jan 1876 | 4 | Traverse Juror | Clearfield Twp | |
| O'DONNELL | David | 8 | The Butler Union | 28 Jan 1861 | 4 | Notice in Partition | ||
| O'DONNELL | Dennis | 6 | Democratic Herald | 21 Jul 1852 | 3 | Administrator's Notice | Donegal Township | |
| O'DONNELL | Dennis | 14 | Parker City Daily | 21 Aug 1876 | 3 | Trial List | ||
| O'DONNELL | Dr. H. M. | 8 | The Butler Union | 28 Jan 1861 | 3 | Advertisement | X | |
| O'DONNELL | Dr. Stephen | 8 | The Butler Union | 28 Jan 1861 | 3 | Advertisement | X | |
| O'DONNELL | E. | 13 | Parker City Daily | 04 Oct 1875 | 3 | Abortion Inquest | ||
| O'DONNELL | Ed. | 13 | Parker City Daily | 23 Sep 1875 | 3 | Foreman | Petrolia | |
| O'DONNELL | Francis | 8 | The Butler Union Herald | 30 Mar 1864 | 3 | Accident | Oakland Twp | |
| O'DONNELL | Franklin | 8 | The Butler Union | 22 Jul 1863 | 3 | Drafted | Donegal Twp | |
| O'DONNELL | Giles | 8 | The Union Herald | 10 Sep 1864 | 3 | Sheriff's Sales | Oakland Twp | |
| O'DONNELL | Hugh | 6 | Democratic Herald | 31 Oct 1855 | 3 | Executor's Notice | Venango Township | |
| O'DONNELL | J. | 14 | Parker City Daily | 29 May 1876 | 3 | Election Results | Parker | |
| O'DONNELL | James | 1 | The Butler Democrat | 11 Oct 1813 | 3 | List of Letters | Butler | X |
| O'DONNELL | James | 8 | The Butler Union | 22 Jul 1863 | 3 | Drafted | Clearfield Twp | |
| O'DONNELL | James | 16 | The Democratic Herald | 24 Feb 1898 | 1 | Death Notice | Clearfield Twp | |
| O'DONNELL | James | 7 | The Democratic Herald | 09 Jan 1856 | 4 | For Rent | ||
| O'DONNELL | Jessie | 8 | The Union Herald | 15 Jun 1864 | 3 | Drafted | Donegal Twp | |
| O'DONNELL | John | 7 | The Democratic Herald | 09 Jan 1856 | 4 | For Rent | X | |
| O'DONNELL | John | 9 | Union Herald | 15 May 1867 | 2 | Estate | Donegal | |
| O'DONNELL | John | 14 | Parker City Daily | 14 Jul 1876 | 3 | Oil Well | Millerstown | |
| O'DONNELL | John | 15 | Connoquenessing Valley News | 12 Mar 1891 | 3 | Property Transfers | Butler | |
| O'DONNELL | Jonathan | 14 | The Butler County Citizen | 19 Jan 1876 | 4 | Traverse Juror | Donegal Twp | |
| O'DONNELL | Joseph | 8 | The Butler Union Herald | 30 Mar 1864 | 3 | Accident | Oakland Twp | |
| O'DONNELL | Margaret | 14 | The Butler Citizen | 10 Aug 1881 | 2 | Register's Notice | Venango Twp | |
| O'DONNELL | Mich. | 13 | Parker City Daily | 10 Jan 1876 | 3 | Present | St. Joe | |
| O'DONNELL | Michael | 8 | The Butler Union Herald | 30 Mar 1864 | 3 | Accident | Oakland Twp | |
| O'DONNELL | Michael | 11 | The Democratic Herald | 08 Feb 1871 | 4 | Sale | ||
| O'DONNELL | Mrs. Mary | 7 | The Democratic Herald | 18 Mar 1857 | 3 | Obituary | Clearfield Twp | |
| O'DONNELL | Nancy | 10 | American Citizen | 02 Aug 1871 | 2 | Married | X | |
| O'DONNELL | Patrick | 11 | Butler County Citizen | 03 Apr 1872 | 2 | Notice | ||
| O'DONNELL | Patrick | 14 | Connoquenessing Valley News | 14 Aug 1879 | 2 | List of Jurors | Venango Twp | |
| O'DONNELL | Patrick L. | 14 | The Butler Citizen | 10 Aug 1881 | 2 | Register's Notice | Venango Twp | |
| O'DONNELL | Phineas | 8 | The Union Herald | 14 May 1862 | 3 | Marriage | Donegal Twp | |
| O'DONNELL | R. L. | 16 | The Democratic Herald | 15 Jul 1898 | 3 | Farm | ||
| O'DONNELL | R. M. | 8 | The Butler Union | 26 Feb 1861 | 2 | Letter to Editor | ||
| O'DONNELL | Samuel | 8 | The Butler Union | 11 Jun 1861 | 3 | Sheriff's Sales | Middlesex Twp | |
| O'DONNELL | Sgt. Joseph | 16 | The Democratic Herald | 01 Oct 1898 | 1 | Discharged | ||
| O'DONNELL | Simon P. | 14 | The Butler Citizen | 07 Jun 1882 | 4 | Killed | ||
| O'DONNELL | Sylvester | 14 | The Millerstown Herald | 15 Jul 1882 | 1 | Harvesting | North Oakland | |
| O'DONNELL | Thomas | 8 | The Butler Union | 21 May 1861 | 3 | List of "Venders" | Middlesex Twp | X |
| O'DONNELL | Thos. | 15 | Connoquenessing Valley News | 22 Aug 1889 | 3 | Found Body | Carbon Center | |
| OELSCHLAGER | Fred J. | 16 | The Democratic Herald | 03 Jun 1898 | 5 | Death Notice | ||
| OERERNSCHLAYER | Catherine | 6 | Democratic Herald | 21 Sep 1853 | 3 | Marriage | Butler Borough | |
| OESTERLING | Bertha | 15 | Connoquenessing Valley News | 26 Feb 1891 | 3 | Marriage License | Summit Twp. | |
| OESTERLING | Elizabeth | 16 | The Democratic Herald | 11 Mar 1898 | 10 | Real Estate Sale | ||
| OESTERLING | Elizabeth Brus | 16 | The Democratic Herald | 08 Apr 1898 | 1 | Murder! | Centre Twp | |
| OESTERLING | J. W. | 15 | Connoquenessing Valley News | 05 Mar 1891 | 3 | House Complete | ||
| OESTERLING | James | 14 | The Democratic Herald | 22 Feb 1882 | 3 | License Application | Zelienople | |
| OESTERLING | James | 16 | The Democratic Herald | 08 Apr 1898 | 1 | Murder! | Centre Twp | |
| OESTERLING | John | 16 | The Democratic Herald | 14 Jan 1898 | 3 | Jury List | Summit Twp | X |
| OESTERLING | John A. | 16 | The Butler Citizen | 07 Jun 19OO | 3 | Marriage License | Carbon Centre | |
| OESTERLING | Jos. | 14 | Connoquenessing Valley News | 20 Mar 1879 | 3 | Granted License | ||
| OESTERLING | Leonard | 7 | The Democratic Herald | 01 Sep 1858 | 3 | List of Causes | ||
| OESTERLING | Mrs. George | 16 | The Democratic Herald | 08 Apr 1898 | 1 | Murder! | Centre Twp | |
| OESTERLING | Mrs. Mary Elizabeth | 15 | Connoquenessing Valley News | 17 Jan 1884 | 3 | Death Notice | ||
| OESTERLING | Peter | 14 | Connoquenessing Valley News | 18 Sep 1879 | 2 | Orphans' Court | Zelienople | |
| OESTERLING | Peter | 15 | Connoquenessing Valley News | 17 Jan 1884 | 3 | Death Notice | X | |
| OESTERLING | William | 16 | The Democratic Herald | 15 Jul 1898 | 3 | Farm | ||
| OESTERMAN | Sarah | 15 | Connoquenessing Valley News | 26 Mar 1891 | 3 | Property Transfer | Buffalo Twp | |
| OFFICERS LIST | 9 | Democratic Herald | 02 Jun 1869 | 3 | Farmers Institute | Townships | ||
| OFFLEY | D. Kenneth | 13 | Parker City Daily | 18 Dec 1875 | 3 | Complimentary Dinner | ||
| OFFLEY | D. Rem. | 13 | Parker City Daily | 24 Nov 1875 | 3 | Returned Home | ||
| OFFLEY | D. Remsen | 13 | Parker City Daily | 22 Sep 1875 | 3 | Assistant Marshall | ||
| OFFLEY | Joseph | 14 | Parker City Daily | 26 Jul 1876 | 3 | Elected | ||
| OFFLEY | Ren. | 14 | Parker City Daily | 15 Jun 1876 | 3 | Oil Man | ||
| OGDEN | E. | 9 | Democratic Herald | 14 Aug 1867 | 4 | Lost | Glade Mills | |
| OGDEN | E. | 9 | Union Herald | 24 Jul 1867 | 2 | Lost & Found | Glade Mill | |
| OGDEN | Hugh | 2 | Butler Sentinel | 06 Mar 1830 | 3 | Sheriff's Sale | Donegal Twp. | |
| OGDEN | John B. | 8 | The Union Herald | 30 Sep 1863 | 3 | Notice | ||
| OGDEN | Mrs. Mary Jane Bauks | 8 | The Union Herald | 10 Sep 1864 | 3 | Death Notice | Penn Twp | |
| OGDEN | Rev. E. | 8 | The Union Herald | 16 Jul 1862 | 2 | County Ticket | Middlesex Twp | |
| OGDEN | Rev. E. | 14 | The Butler Citizen | 10 Aug 1881 | 2 | Burglary | Middlesex Twp | |
| OGDEN | Rev.E. | 6 | Democratic Herald | 3 Oct 1855 | 2 | Political Office Candidate | ||
| OGDEN | Sue | 16 | The Democratic Herald | 01 Jul 1898 | 5 | Graduate | ||
| OGDEN | Thomas | 8 | The Butler Union | 21 May 1861 | 3 | List of "Venders" | Middlesex Twp | X |
| OGDEN | William | 11 | Zieglers Democratic Herald | 12 Feb 1874 | 3 | Court | ||
| OGDEN | 11 | American Citizen | 17 Jan 1872 | 2 | Court Notice | Rev | ||
| OGDEN | 11 | American Citizen | 24 Jan 1872 | 2 | Court Notice | Rev | ||
| OGDEN | 11 | American Citizen | 07 Feb 1872 | 4 | Death | Rev | ||
| OGDEN | Rev. E. | 15 | Connoquenessing Valley News | 26 Mar 1891 | 3 | Wills & Letters | Middlesex Twp. | |
| OGDOS ? | E. | 11 | American Citizen | 07 Feb 1872 | 2 | Marriage | Rev | |
| OGELBY | E. L. | 13 | Parker City Daily | 02 Dec 1875 | 3 | Invitation | ||
| OGILBY | E. L. | 14 | Parker City Daily | 18 Aug 1876 | 3 | Wanted | X | |
| OGILVY | Bessie | 15 | Connoquenessing Valley News | 19 Feb 1891 | 3 | Marriage License | Parker Twp | |
| O'GORMAN | Edith | 14 | Parker City Daily | 09 May 1876 | 3 | Lecture | ||
| O'HARA | Arthur | 1 | The Tree of Liberty | 29 Jul 1806 | 4 | List of Causes | Court of Common Pleas | |
| O'HARA | James | 1 | The Tree of Liberty | 29 Jul 1806 | 3 | Turnpike Road | Allegheny County | |
| O'HARA | Jas. | 15 | Connoquenessing Valley News | 14 Aug 1884 | 2 | Jury List | Karns City | |
| OHARAH | Francis | 1 | The Butler Centinel | 26 Jan 1822 | 1 | Public Notice | Parker Twp. | X |
| O'HARE | Hugh | 13 | Parker City Daily | 13 Mar 1876 | 3 | Titusville Exchange | ||
| O'HARRA | Clara | 16 | The Democratic Herald | 27 May 1898 | 1 | Public School Graduate | ||
| O'HARRA | John | 2 | The Repository | 03 Sep 1830 | 1 | Sheriff's Sale | Muddy Creek Twp. | |
| O'HARRAH | 4 | Butler Intelligencer | 07 Mar 1840 | 5 | Public Notice | Muddycreek | ||
| OHL | A. | 8 | The Butler Union | 15 Apr 1863 | 4 | Elected | Saxonburg | |
| OHL | A. R. | 16 | The Democratic Herald | 06 May 1898 | 5 | District Division | Buffalo Twp | |
| OHL | George E. | 16 | The Democratic Herald | 06 May 1898 | 5 | District Division | Buffalo Twp | |
| OHL | Peter | 14 | The Butler County Citizen | 19 Jan 1876 | 4 | Traverse Juror | Jefferson Twp | |
| OHLER | Katrina | 16 | The Democratic Herald | 27 May 1898 | 1 | 9th Grade Graduate | ||
| OHRT | H. E. | 14 | Parker City Daily | 104 Aug 1876 | 3 | Civil Engineer | ||
| OIL STRIKES | New | 10 | American Citizen | 06 April 1870 | 2 | Locations | ||
| OILER | Rev. W. E. | 15 | The Semi-Monthly | 15 Jan 1883 | 2 | Purchased House | ||
| OINTER | Miss Rebecca | 1 | The Butler Democrat | 11 Oct 1813 | 3 | Lost | Clearfield County | |
| O'KANE | Daniel | 11 | American Citizen | 14 Feb 1872 | 2 | Political | ||
| O'KANE | Mary | 11 | American Citizen | 14 Feb 1872 | 2 | Political | ||
| OKELY, ESQ | John | 1 | The Butler Sentinel | 28 Sep 1822 | 3 | Marriage | Harmony | X |
| OKESON | S. T. | 15 | Connoquenessing Valley News | 11 Jul 1889 | 3 | Advertisement | Portersville | X |
| OLABAUGH | Levi | 14 | Parker City Daily | 15 Jun 1876 | 3 | Building | Emlenton | |
| OLBERT | Harvey | 8 | The Union Herald | 30 Sep 1863 | 3 | Notice to Collectors | ||
| OLD | Henry | 8 | The Butler Union | 22 Jul 1863 | 3 | Drafted | Centreville & Slippery Rock Twp | |
| OLD ECONOMY | 6 | Democratic Herald | 26 May 1852 | 1 | Travel | Contemporary description of the Community | ||
| OLDEMUK | J. | 11 | Butler County Citizen | 27 Mar 1872 | 3 | Advertisement | Dr | |
| OLDEMUK | J. W. | 11 | Butler County Citizen | 27 Mar 1872 | 3 | Advertisement | Dr | |
| OLDEMUK | T. L. | 11 | Butler County Citizen | 27 Mar 1872 | 3 | Advertisement | Dr | |
| OLDEN | Miss Tilla | 13 | Parker City Daily | 03 Jan 1876 | 3 | Selected | ||
| OLDEN | Miss Tillie | 14 | Parker City Daily | 21 Jun 1876 | 3 | Visiting | X | |
| OLDHAM | James R. C. | 7 | The Democratic Herald | 10 Sep 1856 | 3 | Sheriff's Sales | Butler Twp. | |
| OLDHAM | Mrs. Lizzie | 16 | The Butler County Record | 22 Mar 1900 | 2 | Ill | ||
| OLDSHUE | Dr. | 11 | The Democratic Herald | 15 Feb 1871 | 2 | Advertisement | ||
| OLDSHUE | J. W. | 11 | American Citizen | 17 Jan 1872 | 3 | Advertisement | Dr | |
| OLDSHUE | J. W. | 11 | Butler County Citizen | 17 Apr 1872 | 3 | Advertisement | ||
| OLDSHUE | J. W. | 11 | Butler County Citizen | 18 Sep 1872 | 3 | Advertisement | ||
| OLDSHUE | J. W. | 11 | Butler County Citizen | 02 Sep 1874 | 3 | Advertisement | ||
| OLDSHUE | L. | 11 | American Citizen | 17 Jan 1872 | 3 | Advertisement | Dr | |
| OLDSHUE | L. | 11 | Butler County Citizen | 18 Sep 1872 | 3 | Advertisement | ||
| OLDSHUE | L. D. | 11 | Butler County Citizen | 17 Apr 1872 | 3 | Advertisement | ||
| OLDSHUE | L. P. | 11 | Butler County Citizen | 02 Sep 1874 | 3 | Advertisement | ||
| OLDSHUE | T. L. | 11 | American Citizen | 17 Jan 1872 | 3 | Advertisement | Dr | |
| OLDSHUE | T. L. | 11 | Butler County Citizen | 17 Apr 1872 | 3 | Advertisement | ||
| OLDSHUE | T. L. | 11 | Butler County Citizen | 18 Sep 1872 | 3 | Advertisement | ||
| OLDSHUE | T. L. | 11 | Butler County Citizen | 02 Sep 1874 | 3 | Advertisement | ||
| OLDSMAN | Dr. | 11 | The Democratic Herald | 29 Mar 1871 | 2 | Medical | ||
| OLDSUCK | 11 | The Democratic Herald | 19 Apr 1871 | 2 | Advertisement | Dr | X | |
| O'LEARY | Arthur | 11 | The Democratic Herald | 29 Mar 1871 | 4 | Director | ||
| O'LEARY | Arthur | 11 | The Democratic Herald | 15 Feb 1871 | 3 | Director | ||
| O'LEARY | F. A. | 11 | American Citizen | 10 Jan 1872 | 5 | Advertisement | ||
| O'LEARY | F. A. | 11 | American Citizen | 17 Jan 1872 | 4 | Advertisement | ||
| O'LEARY | F. A. | 11 | American Citizen | 24 Jan 1872 | 4 | Advertisement | ||
| O'LEARY | F. A. | 11 | American Citizen | 31 Jan 1872 | 4 | Advertisement | ||
| O'LEARY | F. A. | 11 | American Citizen | 07 Feb 1872 | 4 | Advertisement | ||
| O'LEARY | F. A. | 11 | American Citizen | 14 Feb 1872 | 4 | Advertisement | ||
| O'LEARY | F. A. | 11 | American Citizen | 21 Feb 1872 | 4 | Advertisement | ||
| O'LEARY | F. A. | 11 | American Citizen | 28 Feb 1872 | 5 | Advertisement | ||
| O'LEARY | F. A. | 11 | Butler County Citizen | 13 Mar 1872 | 4 | Advertisement | ||
| O'LEARY | F. A. | 11 | Butler County Citizen | 20 Mar 1872 | 4 | Advertisement | ||
| O'LEARY | F. A. | 11 | Butler County Citizen | 27 Mar 1872 | 4 | Advertisement | ||
| O'LEARY | F. A. | 11 | Butler County Citizen | 03 Apr 1872 | 4 | Advertisement | ||
| O'LEARY | F. A. | 11 | Butler County Citizen | 10 Apr 1872 | 4 | Advertisement | ||
| OLEYPOOL | 4 | Butler Intelligencer | 07 Mar 1840 | 5 | Public Notice | Parker Township | X | |
| OLIPHANT | James | 1 | The Butler Sentinel | 24 Jan 1824 | 3 | List of Letters | Harmony | X |
| OLIPHANT | Jas. | 1 | The Butler Centinel | 23 Jan. 1821 | 3 | List of Letters | Harmony | X |
| OLIVER | C. E. | 16 | Connoquenessing Valley News | 21 Dec 1899 | 1 | Property Transfer | Fairview Twp | |
| OLIVER | D. H. | 11 | Boys Echo | 01 Jun 1873 | 4 | Advertisement | ||
| OLIVER | Earl | 16 | The Democratic Herald | 01 Jul 1898 | 5 | Graduate | ||
| OLIVER | Geo. | 8 | The Union Herald | 01 Mar 1865 | 3 | Receipts & Expenditures | Portersville | X |
| OLIVER | H. | 15 | Connoquenessing Valley News | 19 Jun 1890 | 2 | For Sale | Portersville | X |
| OLIVER | Hendrson | 9 | Democratic Herald | 06 Jan 1869 | 3 | Registers Notice | Portersville | |
| OLIVER | J. M. | 9 | Democratic Herald | 06 Jan 1869 | 3 | Registers Notice | Portersville | |
| OLIVER | James | 8 | The Butler Union | 17 Sep 1861 | 3 | Juror | Venango Twp | |
| OLIVER | Jane | 9 | Union Herald | 31 Oct 1866 | 3 | Property Appraisal | ||
| OLIVER | Jeanette | 11 | American Citizen | 21 Feb 1872 | 1 | Death Notice | ||
| OLIVER | Jeanette | 11 | American Citizen | 28 Feb 1872 | 5 | Court | ||
| OLIVER | Jeannette | 11 | American Citizen | 14 Feb 1872 | 2 | Estate | ||
| OLIVER | John | 1 | The Butler Democrat | 11 Oct 1813 | 4 | Advertisement | Portersville | |
| OLIVER | John | 1 | The Butler Democrat | 01 Nov 1813 | 4 | Traverse Juror | Muddycreek Twp. | X |
| OLIVER | John | 4 | Butler Intelligencer | 18 Jul 1840 | 1 | July 4 Celebration | Portersville | |
| OLIVER | John | 4 | Butler Intelligencer | 18 Jul 1840 | 1 | July 4 Celebration | Portersville | |
| OLIVER | John | 4 | Butler Intelligencer | 01 Aug 1840 | 3 | Stray Mare | Muddycreek Township | |
| OLIVER | John | 7 | The Democratic Herald | 23 Jul 1856 | 3 | Fair Committee | Portersville | X |
| OLIVER | John | 8 | The Butler Union | 15 Apr 1863 | 4 | Elected | Portersville | |
| OLIVER | John | 9 | Union Herald | 31 Oct 1866 | 3 | Property Appraisal | ||
| OLIVER | John | 9 | Union Herald | 20 Mar 1867 | 1 | Murder Trial | Portersville | |
| OLIVER | John | 9 | Democratic Herald | 29 Apr 1868 | 3 | Livery Stable | Butler | |
| OLIVER | John P. | 9 | American Citizen | 26 May 1869 | 2 | Sheriff Sale | Portersville | |
| OLIVER | Jos. E. | 11 | Butler County Citizen | 11 Sep 1872 | 3 | Court | ||
| OLIVER | Melissa | 9 | Union Herald | 20 Mar 1867 | 1 | Murder Trial | Portersville | |
| OLIVER | Mrs. Geo. H. | 14 | Connoquenessing Valley News | 06 Nov 1878 | 2 | Drowned | ||
| OLIVER | Norman | 16 | The Democratic Herald | 01 Jul 1898 | 5 | Graduate | ||
| OLIVER | Robert W. | 1 | The Butler Democrat | 11 Oct 1813 | 3 | List of Letters | Butler | X |
| OLIVER | W. J. | 8 | The Butler Union | 21 May 1861 | 3 | List of "Venders" | Middlesex Twp | X |
| OLIVER | Wm. | 8 | The Union Herald | 21 Dec 1864 | 3 | Killed | ||
| OLLENDORFF | 11 | The Democratic Herald | 19 Apr 1871 | 2 | Advertisement | |||
| OLLENDORFF | 11 | The Democratic Herald | 10 May 1871 | 2 | Advertisement | |||
| OLLENDORFF | 11 | The Democratic Herald | 21 Jun 1871 | 1 | Advertisement | |||
| OLLENDORFF | 11 | The Democratic Herald | 28 Jun 1871 | 1 | Advertisement | |||
| OLLER | J. M. | 16 | The Democratic Herald | 24 Jun 1898 | 6 | Week in Court | Kamerer | |
| OLLER | Rev. W. E. | 14 | Semi-Monthly | 01 Sep 1882 | 3 | Elected | ||
| OLMSTEAD | Joseph B. | 13 | Parker City Daily | 11 Dec 1875 | 3 | Bankrupt | ||
| OLMSTED | Arthur G. | 11 | Butler County Citizen | 02 Sep 1874 | 2 | Politics | ||
| OLSON | C. A. | 11 | Butler County Citizen | 02 Sep 1874 | 3 | News | ||
| OLSON | Gertrude | 16 | The Democratic Herald | 16 Dec 1898 | 1 | Grand Jury Returns | ||
| OLSON | Samuel | 11 | Butler County Citizen | 03 Apr 1872 | 4 | Official | ||
| ONDLE | Jacob | 8 | The Butler Union | 22 Jul 1863 | 3 | Drafted | Connoquenessing Twp | |
| ONDLE | William | 8 | The Butler Union | 22 Jul 1863 | 3 | Drafted | Connoquenessing Twp | |
| O'NEAL | William | 8 | The Union Herald | 29 Jun 1864 | 3 | Enrollment Report | Clearfield Twp | |
| O'NEAL | Wm. A. | 8 | The Butler Union | 15 Apr 1863 | 4 | Elected | Clearfield Twp | |
| O'NEIEL | H. F. | 13 | Parker City Daily | 27 Jan 1876 | 3 | Director | Millerstown | X |
| ONEIL | Patrick, Rev. | 5 | Butler Intelligencer | 13 Nov 1841 | 3 | Sheriff Sale | Donegal | |
| O'NEIL | Barney | 11 | Butler County Citizen | 24 Dec 1873 | 2 | Court | ||
| O'NEIL | Barney | 11 | Butler County Citizen | 07 Jan 1874 | 3 | Court | ||
| O'NEIL | Dan | 16 | The Democratic Herald | 15 Jul 1898 | 3 | Farm | ||
| O'NEIL | Emma | 16 | The Democratic Herald | 29 Apr 1898 | 1 | Land Transfers | Venango Twp | |
| O'NEIL | Francis | 11 | Butler County Citizen | 24 Dec 1873 | 2 | Court | ||
| O'NEIL | Francis | 11 | Butler County Citizen | 07 Jan 1874 | 3 | Court | ||
| O'NEIL | H. F. | 11 | Butler County Citizen | 18 Nov 1874 | 2 | Politics | ||
| O'NEIL | J. Palmer | 13 | Parker City Daily | 05 Nov 1875 | 3 | Burglary | ||
| O'NEIL | Patrick | 11 | Butler County Citizen | 24 Dec 1873 | 2 | Court | ||
| O'NEIL | Patrick | 11 | Butler County Citizen | 07 Jan 1874 | 3 | Court | ||
| O'NEIL | Patsy | 13 | Parker City Daily | 30 Sep 1875 | 3 | Arrested | ||
| O'NEIL | 11 | American Citizen | 24 Jan 1872 | 3 | Advertisement | |||
| O'Neil | Charley | 13 | Parker City Daily | 21 Jan 1876 | 3 | Medical Aid | Millerstown | |
| O'NEIL, ESQ. | H. F. | 13 | Parker City Daily | 21 Jan 1876 | 3 | Medical Aid | Millerstown | |
| ONEILL | Lawrence | 16 | The Democratic Herald | 04 Feb 1898 | 1 | Minor Child | ||
| ONEILL | Myrtle | 16 | The Democratic Herald | 04 Feb 1898 | 1 | Minor Child | ||
| ONEILL | Ralph | 16 | The Democratic Herald | 04 Feb 1898 | 1 | Minor Child | ||
| ONEILL | Ruth | 16 | The Democratic Herald | 04 Feb 1898 | 1 | Minor Child | ||
| O'NEILL | Dennis | 13 | Parker City Daily | 08 Jan 1876 | 3 | Letter | Petrolia | |
| O'NEILL | H. F. | 14 | Parker City Daily | 20 Jun 1876 | 3 | Delegate | Millerstown | X |
| O'NEILL | William | 8 | The Union Herald | 15 Jun 1864 | 3 | Drafted | Clearfield Twp | |
| O'NEILL, REV. | Patrick | 5 | Butler Intelligencer | 25 May 1841 | 3 | Sheriff Sale | Donegal | |
| O'NIEL | Mary | 8 | The Union Herald | 25 Nov 1863 | 3 | Marriage | Clearfield Twp. | |
| ONSLOW | James | 13 | Parker City Daily | 21 Oct 1875 | 3 | Keystone Club | ||
| ONSLOW | Jim | 14 | Parker City Daily | 04 May 1876 | 3 | "Kegs of Bock" | ||
| OPPENHEIM | Leo | 14 | Parker City Daily | 08 May 1876 | 1 | Brokerage | ||
| OPPENHEIMER | Miss Nannie | 15 | Connoquenessing Valley News | 25 Jul 1889 | 3 | Fatal Accident | Harmony | |
| OPRAY | James | 1 | The Butler Sentinel | 04 Jan 1823 | 3 | List of Letters | Butler | X |
| OPRE | J. H. G. | 11 | Butler County Citizen | 25 Sep 1872 | 2 | Court | ||
| OPRE | J. H. G. | 11 | Butler County Citizen | 02 Oct 1872 | 2 | Court | ||
| ORBAUGH | George | 1 | The Butler Sentinel | 03 Dec 1825 | 3 | Marriage | Slipperyrock Twp. | |
| ORBIN | George | 11 | The Democratic Herald | 29 Mar 1871 | 3 | Church | ||
| ORBISON | Alexander | 7 | The Democratic Herald | 09 Jan 1856 | 4 | Unclaimed Mail | X | |
| ORBISON | J. B. | 11 | Butler County Citizen | 20 Mar 1872 | 3 | Court | ||
| ORBISON | J. B. | 16 | The Democratic Herald | 16 Sep 1898 | 2 | Assignees Sale | Donegal Twp | |
| ORBISON | J. B. | 14 | The Butler Citizen | 08 Jun 1881 | 3 | County Convention | Donegal Twp | |
| ORBISON | Joseph | 8 | The Butler Union | 22 Jul 1863 | 3 | Drafted | Donegal Twp | |
| ORBISON | Josiah | 16 | The Butler County Record | 22 Mar 1900 | 2 | Jury List | Donegal Twp | |
| ORCER | Matthew | 7 | The Democratic Herald | 18 Feb 1857 | 2 | Receipts & Expenditures | Buffalo Twp | X |
| ORENS | James | 7 | The Missionary | 23 Jun 1859 | 2 | Contribution | ||
| ORLON | George | 13 | Parker City Daily | 05 Oct 1875 | 3 | Honor Roll | Parker City | |
| ORLTON | John | 1 | The Butler Centinel | 07 Oct 1820 | 3 | List of Letters | Butler | X |
| ORLTON | John | 1 | The Butler Centinel | 02 Jan 1821 | 2 | List of Letters | Butler | |
| ORMOND | A. P. | 6 | Democratic Herald | 21 Apr 1852 | 4 | Business | Butler Co. | |
| ORMOND | A. P. | 6 | Democratic Herald | 2 May 1855 | 2 | Robbery | Butler Borough | |
| ORMSBAY | George | 1 | The Butler Centinel | 10 Jul 1821 | 3 | List of Letters | Butler | X |
| ORMSBY | Dr. | 2 | The Repository | 03 Sep 1836 | 3 | Advertisement | ||
| ORMSBY | Dr. | 7 | The Democratic Herald | 19 Mar 1856 | 3 | Petitions | ||
| ORMSBY | Oliver | 1 | The Butler Centinel | 27 Feb 1821 | 3 | Orphans' Court Sale | X | |
| O'ROAKE | James | 11 | Butler County Citizen | 24 Dec 1873 | 2 | Court | ||
| O'RORK | John T. | 14 | The Butler County Citizen | 19 Jan 1876 | 4 | List of Causes | ||
| O'ROUKE | James | 11 | Butler County Citizen | 07 Jan 1874 | 3 | Court | ||
| OROURKE | John | 13 | Parker City Daily | 13 Dec 1875 | 3 | Injured | ||
| O'ROURKE | Mrs. Thos. | 15 | Connoquenessing Valley News | 11 Jul 1889 | 3 | Had Visitor | ||
| O'ROURKE | Thomas | 15 | Connoquenessing Valley News | 03 Apr 1890 | 3 | Notice | ||
| ORPHAN'S HOME | St. Paul’s | 10 | American Citizen | 20 April 1870 | 3 | Visiting hours | ||
| ORR | A. J. | 1 | The Butler Centinel | 02 Jan 1821 | 2 | List of Letters | Butler | |
| ORR | Andrew | 2 | Butler Sentinel | 01 Dec 1827 | 3 | Obituary | ||
| ORR | E. | 8 | The Butler Union | 28 Jan 1861 | 3 | Advertisement | X | |
| ORR | E. | 11 | American Citizen | 17 Jan 1872 | 2 | Death Notice | Mrs | |
| ORR | General | 14 | Parker City Daily | 24 May 1876 | 3 | Died | Kittanning | |
| ORR | George W. | 16 | The Democratic Herald | 29 Jul 1898 | 2 | Will | Forward Twp | |
| ORR | Grier C. | 13 | Parker City Daily | 18 Nov 1875 | 3 | In Memoriam | ||
| ORR | Hulda B. | 16 | The Democratic Herald | 11 Mar 1898 | 10 | Week in Court | Forward Twp | |
| ORR | J. M. | 8 | The Union Herald | 23 Jul 1862 | 3 | Auditor's Notice | ||
| ORR | J. P. | 11 | Butler County Citizen | 21 Aug 1872 | 1 | Officials | X | |
| ORR | J. W. | 11 | Butler County Citizen | 20 Mar 1872 | 2 | Crime | ||
| ORR | J. W. | 13 | Parker City Daily | 21 Dec 1875 | 3 | Oration | Foxburg | X |
| ORR | James | 14 | The Butler County Citizen | 19 Jan 1876 | 4 | Traverse Juror | Adams Twp | |
| ORR | James | 16 | The Democratic Herald | 29 Apr 1898 | 1 | Appointed | Adams Twp | X |
| ORR | James H. | 14 | Parker City Daily | 14 Jul 1876 | 3 | Sold Hotel | St. Joe | |
| ORR | James W. | 16 | The Democratic Herald | 28 Jan 1898 | 1 | Verdict | ||
| ORR | Jim | 13 | Parker City Daily | 16 Sep 1875 | 3 | Changed Hands | St. Joe | |
| ORR | Jim | 14 | Parker City Daily | 28 Apr 1876 | 2 | Proprietor | St. Joe | X |
| ORR | Jno. P. | 14 | Parker City Daily | 30 May 1876 | 3 | Artist | Butler | |
| ORR | John | 4 | Butler Intelligencer | 07 Mar 1840 | 5 | Public Notice | Mercer Township | |
| ORR | John | 14 | Karns City Telephone | 17 Sep 1881 | 3 | Subscription | Petrolia | |
| ORR | John P | 7 | The Democratic Herald | 22 Sep 1858 | 2 | Injured | ||
| ORR | John P. | 9 | Union Herald | 14 Mar 1866 | 4 | Advertisement | Butler | |
| ORR | John P. | 9 | Union Herald | 13 June 1866 | 2 | Candidate/Clerk | Butler Boro | |
| ORR | John P. | 11 | Zieglers Democratic Herald | 12 Feb 1874 | 2 | Official | ||
| ORR | John P. | 11 | Zieglers Democratic Herald | 12 Feb 1874 | 4 | Politics | ||
| ORR | John P. | 8 | The Butler Union | 29 Oct 1861 | 2 | Advertisement | X | |
| ORR | John P. | 14 | Semi-Monthly | 15 Dec 1882 | 3 | Died | ||
| ORR | L. P. | 11 | Butler County Citizen | 17 Jul 1872 | 1 | Politics | X | |
| ORR | Robert | 1 | The Butler Centinel | 13 Nov 1821 | 3 | List of Letters | Harmony | X |
| ORR | Robert, Jr | 2 | Butler Sentinel | 08 July 1826 | 3 | Delegate | ||
| ORR | Sam'l. | 8 | The Butler Union | 07 May 1861 | 2 | War Meeting | Sunbury | |
| ORR | Simon F. | 14 | Parker City Daily | 16 Jun 1876 | 3 | Fire | ||
| ORR | W. | 11 | Butler County Citizen | 10 Sep 1873 | 2 | Court | ||
| ORR | W. H. | 13 | Millerstown Review | 03 Aug 1876 | 3 | Honor Roll | Harrisville Station | |
| ORR | William | 8 | The Butler Union | 21 May 1861 | 3 | Sheriff's Sales | Middlesex Twp | X |
| ORR | Wm. | 14 | The Butler County Citizen | 19 Jan 1876 | 4 | Traverse Juror | Mercer Twp | |
| ORR | 11 | American Citizen | 24 Jan 1872 | 2 | Death Notice | Mrs | ||
| ORR | Ellen | 16 | The Democratic Herald | 13 May 1898 | 8 | Land Transfers | Connoquenessing | |
| ORRELL | Mary | 16 | Connoquenessing Valley News | 28 Nov 1899 | 1 | Property Transfer | Butler | |
| ORRIE | Mrs. Mary | 16 | Connoquenessing Valley News | 21 Dec 1899 | 1 | Property Transfer | Butler | |
| ORRIS | Geo. | 14 | Parker City Daily | 01 Jun 1876 | 3 | Arrested | Petrolia | |
| ORRIS | J. | 11 | Butler County Citizen | 20 Mar 1872 | 3 | Court | ||
| ORRIS | W. S. | 14 | Parker City Daily | 03 May 1876 | 3 | Marriage | Karns City | |
| ORRIS | William | 16 | The Democratic Herald | 11 Mar 1898 | 10 | Breaking & Entering | ||
| ORRIS | Winfield S. | 16 | The Democratic Herald | 13 May 1898 | 1 | Pension | X | |
| ORRO | B. | 8 | The Butler Union | 11 Feb 1861 | 3 | Advertisement | X | |
| ORRO | Charlotte L. | 9 | Union Herald | 14 Nov 1866 | 3 | Marriage | Butler | |
| ORSBORN | Harvey | 9 | Union Herald | 13 June 1866 | 2 | Candidate/Sheriff | Middlesex | |
| ORSON | George | 13 | Parker City Daily | 25 Jan 1876 | 3 | Attending School | ||
| ORT | Dr. E. B. | 7 | The Democratic Herald | 01 Sep 1858 | 4 | Advertisement | ||
| ORTON | Mrs. Sarah | 13 | Parker City Daily | 20 Oct 1875 | 3 | Building Residence | ||
| ORUM | M. L. | 14 | Parker City Daily | 21 Jul 1876 | 3 | New Patent | Philadelphia | |
| ORWIG | John | 4 | Butler Intelligencer | 08 Feb 1840 | 3 | Sheriff's Sale | Centreville | |
| OSBORN | A. W. | 15 | The Semi-Monthly | 01 Jan 1883 | 6 | Home for Holidays | Millerstown | |
| OSBORN | B. H. | 15 | Semi-Monthly | 15 Mar 1884 | 2 | Moved Away | ||
| OSBORN | D. | 15 | Connoquenessing Valley News | 05 Mar 1891 | 3 | Director | Butler | |
| OSBORN | H. | 9 | Union Herald | 14 Mar 1866 | 3 | Sale | Middlesex | |
| OSBORN | Harvey | 8 | The Union Herald | 30 Sep 1863 | 3 | Committee of Vigilance | Middlesex Twp | |
| OSBORN | Harvey | 14 | The Butler Citizen | 10 Aug 1881 | 4 | County Fair | ||
| OSBORN | John | 9 | American Citizen | 30 Jun 1869 | 3 | Executors Notice | Fairview | |
| OSBORN | Josiah | 11 | American Citizen | 14 Feb 1872 | 3 | Official | ||
| OSBORN | Josiah | 11 | American Citizen | 21 Feb 1872 | 1 | Official | ||
| OSBORN | Josiah | 11 | American Citizen | 28 Feb 1872 | 5 | Official | ||
| OSBORN | Samuel | 9 | Union Herald | 30 May 1866 | 3 | Sheriff Sale | ||
| OSBORN | W. M. | 15 | Connoquenessing Valley News | 22 Aug 1889 | 2 | New House | Valencia | |
| OSBORN, MRS. | John | 9 | American Citizen | 29 Sep 1869 | 3 | Appraisement List | Fairview | |
| OSBORNE | A. W. | 14 | Semi-Monthly | 01 Jan 1881 | 3 | Visiting | Indiana | |
| OSBORNE | D. | 15 | Connoquenessing Valley News | 21 Aug 1890 | 3 | Officer | Butler | X |
| OSBORNE | Dr. | 14 | Parker City Daily | 10 Jul 1876 | 3 | Escaped | Titusville | |
| OSBORNE | Dr. J. | 16 | Connoquenessing Valley News | 28 Nov 1899 | 1 | New Daughter | Harmony | |
| OSBORNE | Dr. J. A. | 16 | Connoquenessing Valley News | 28 Nov 1899 | 2 | Advertisement | Harmony | X |
| OSBORNE | James A. | 16 | The Democratic Herald | 10 Jun 1898 | 8 | Marriage License | Harmony | |
| OSBORNE | John | 11 | East Brady Independent | 04 Mar 1871 | 4 | Death Notice | ||
| OSBORNE | Miss Blance | 14 | Semi-Monthly | 01 Sep 1882 | 3 | Returned Home | ||
| OSBORNE | S. J. | 14 | Parker City Daily | 13 Jul 1876 | 3 | Escaped from Jail | Meadville | |
| OSBURG, MRS. | John | 9 | Democratic Herald | 22 Sep 1869 | 3 | Appraisement List | Fairview | |
| OSBURN | Harvey | 11 | Butler County Citizen | 26 Jun 1872 | 2 | Politics | ||
| OSBURN | Jane | 14 | Butler Citizen | 14 May 1879 | 2 | Sheriff's Sale | Concord Twp | X |
| OSBURN | William | 7 | The Democratic Herald | 26 Mar 1856 | 3 | Administrator's Notice | Portersville | X |
| OSBURN | H. | 9 | Democratic Herald | 30 Sep 1868 | 3 | Pole Raising | Middlesex | |
| OSBURN | Miss Lou | 14 | Semi-Monthly | 15 Oct 1882 | 3 | Returned Home | ||
| OSBURNE | Harvey | 9 | Democratic Herald | 10 Feb 1869 | 4 | Death | Penn | |
| OSBURNE, MR. | 9 | Democratic Herald | 10 Feb 1869 | 4 | Death | Penn | ||
| OSENBAUGH | John | 8 | The Union Herald | 01 Oct 1864 | 2 | Wounded | ||
| OSENBAUGH | Nellie | 16 | The Democratic Herald | 18 Feb 1898 | 1 | Land Transfers | Butler | |
| OSGOOD | Lucius | 11 | Butler County Citizen | 18 Sep 1872 | 2 | Trustee | ||
| O'SHEA | 11 | The Democratic Herald | 29 Mar 1871 | 1 | Church | Rev. | ||
| O'SHEA | 11 | The Democratic Herald | 19 Apr 1871 | 1 | Church | Rev | X | |
| O'SHEA | 11 | The Democratic Herald | 08 Feb 1871 | 2 | Church | |||
| O'SHEA | 11 | The Democratic Herald | 21 Jun 1871 | 1 | Church | Rev | ||
| O'SHEA | 11 | The Democratic Herald | 28 Jun 1871 | 1 | Church | Rev | ||
| O'SHEA | 11 | Zieglers Democratic Herald | 12 Feb 1874 | 2 | Church | Rev | ||
| OSMER | Elihu E. | 2 | Butler Sentinel | 02 Aug 1828 | 3 | Domestic Attachment | Slippery Rock Twp. | |
| OSMER | J. H. | 13 | Parker City Daily | 16 Oct 1875 | 3 | Address | Franklin | |
| OSMER | J. H. | 14 | Parker City Daily | 19 May 1876 | 3 | Welcoming Speech | ||
| OSMER | Mrs. A. P. | 13 | Parker City Daily | 21 Feb 1876 | 3 | Suicide | Jamestown, N.Y. | |
| OSMER | Mrs. R. A. | 13 | Parker City Daily | 21 Feb 1876 | 3 | Drowned | Jamestown, N.Y. | |
| OSMER | Omar | 13 | Parker City Daily | 13 Jan 1876 | 3 | Assignee | ||
| OSMER | R. A. | 13 | Parker City Daily | 21 Feb 1876 | 3 | Sister-in-law | Jamestown, N.Y. | |
| OSTENDORFF | Charles | 11 | American Citizen | 28 Feb 1872 | 3 | Marriage | ||
| OSTERLING | Elizabeth | 14 | Connoquenessing Valley News | 06 Feb 1879 | 2 | Vendue | ||
| OSTERLING | Peter | 14 | Connoquenessing Valley News | 06 Feb 1879 | 2 | Vendue | ||
| OSTERMAN | Sarah | 13 | Parker City Daily | 11 Apr 1876 | 3 | Trial List | ||
| OSTMAN | Elias | 14 | The Democratic Herald | 22 Feb 1882 | 3 | Sheriff's Sales | Allegheny Twp | |
| OSTOBY | Rev. J. T. | 13 | Parker City Daily | 27 Oct 1875 | 3 | Preaching | Petroleum Centre | |
| OSTRAUDER | Edna | 16 | The Democratic Herald | 27 May 1898 | 1 | Public School Graduate | ||
| OTT | John | 6 | Democratic Herald | 21 Jan 1852 | 3 | Executor's Notice | Clearfield Township | |
| OTT | Martin | 1 | The Butler Democrat | 11 Oct 1813 | 3 | German & French Letters | Butler | X |
| OTT | Martin | 14 | Connoquenessing Valley News | 02 Jan 1879 | 1 | Injured | ||
| OTTERMAN | Miss Bessie | 16 | Connoquenessing Valley News | 28 Nov 1899 | 1 | Entertained | ||
| OTTERMAN | Mrs. A. G. | 16 | The Democratic Herald | 03 Jun 1898 | 4 | Sunday School Association | ||
| OTTERMAN | Rev. J. W. | 16 | The Butler Citizen | 07 Jun 19OO | 2 | Visiting | Zelienople | |
| OTTING | Rev. | 15 | Connoquenessing Valley News | 19 Mar 1891 | 3 | Petition | Harmony | |
| OTTING | Rev. E.H. | 15 | Connoquenessing Valley News | 11 Jul 1889 | 3 | Marriage | Harmony | |
| OTTINGER | Frederick | 8 | The Butler Union | 15 Apr 1863 | 4 | Elected | Millerstown | |
| OTTO | Agnes Y. | 15 | Connoquenessing Valley News | 04 Jun 1891 | 2 | Wills & Letters | Butler | |
| OTTO | Anna | 10 | American Citizen | 15 Nov 1871 | 2 | Married | ||
| OTTO | C. | 8 | The Democratic Herald | 23 Jan 1861 | 2 | Oil Meeting | ||
| OTTO | C. | 14 | Butler Citizen | 14 May 1879 | 2 | Sheriff's Sale | Butler | X |
| OTTO | Christian | 4 | Butler Intelligencer | 26 Sep 1840 | 2 | Harrison Convention | Secretary | |
| OTTO | Christian | 7 | The Democratic Herald | 03 Dec 1856 | 3 | Advertisement | X | |
| OTTO | Christian | 8 | The Democratic Herald | 24 Apr 1861 | 2 | Volunteer | ||
| OTTO | Christian | 15 | Connoquenessing Valley News | 04 Jun 1891 | 2 | Wills & Letters | Butler | |
| OTTO | Christian | 16 | The Democratic Herald | 10 Jun 1898 | 4 | Orphan's Court | ||
| OTTO | Daniel | 8 | The Butler Union Herald | 09 Mar 1864 | 3 | Sheriff's Sales | Cranberry Twp | |
| OTTO | Emma C. | 15 | Connoquenessing Valley News | 18 Jun 1891 | 2 | Marriage License | Cranberry Twp | |
| OTTO | George B. | 8 | The Butler Union | 29 Apr 1863 | 3 | Marriage | ||
| OTTO | Mrs. A. E. | 15 | Connoquenessing Valley News | 14 May 1891 | 4 | Death Notice | Harmony | |
| OTTO | Mrs. B. F. | 16 | The Butler County Observer | 27 June 1901 | 1 | Visiting | ||
| OTTO | Peter | 7 | The Democratic Herald | 10 Jun 1857 | 3 | Vendors | Harmony | |
| OTTO | Peter | 11 | Butler County Citizen | 08 May 1872 | 2 | Mercantile Appraisal | ||
| OTTO | Peter | 11 | Butler County Citizen | 15 May 1872 | 2 | Mercantile Appraisal | ||
| OTTO | Peter | 14 | Connoquenessing Valley News | 27 Mar 1879 | 3 | Marriage | Harmony | X |
| OTTO | William | 16 | The Democratic Herald | 09 Sep 1898 | 3 | Telegram | Butler | |
| OTTO | William R. | 11 | American Citizen | 24 Jan 1872 | 2 | Marriage Notice | ||
| OTTO | Zachariah | 14 | Butler Citizen | 14 May 1879 | 1 | Juror | Cranberry Twp | |
| OULD | Samuel | 1 | The Butler Democrat | 11 Oct 1813 | 3 | List of Letters | Butler | X |
| OUTAPER | Christian | 7 | The Democratic Herald | 18 Mar 1857 | 3 | Licenses | Millerstown | |
| OVERHEIM | D. | 13 | Parker City Daily | 08 Jan 1876 | 3 | Finance Committee | ||
| OVERHEIM | John | 13 | Parker City Daily | 25 Jan 1876 | 3 | Attending School | ||
| OVERHEIM | Wm. | 13 | Parker City Daily | 25 Jan 1876 | 3 | Attending School | ||
| OVERHELM | Katie | 16 | The Democratic Herald | 27 May 1898 | 1 | Public School Graduate | Katie | |
| OVERLIGHTER | John | 14 | Connoquenessing Valley News | 13 Sep 1883 | 3 | Narrow Escape | ||
| OVERY | J. | 11 | Butler County Citizen | 18 Nov 1874 | 2 | Politics | ||
| OVERY | J. | 13 | Millerstown Review | 03 Aug 1876 | 1 | Pipeline | ||
| OVERY | James | 13 | Parker City Daily | 19 Oct 1875 | 3 | Oil Well | ||
| OVERY | Joe | 13 | Parker City Daily | 11 Nov 1875 | 3 | Oil Well | Millerstown | |
| OVERY | Joe | 14 | Parker City Daily | 26 May 1876 | 3 | Oil Well | ||
| OVERY | Jos. | 13 | Parker City Daily | 22 Jan 1876 | 3 | Oil Well | St. Joe | |
| OVERY | Jos. | 14 | Parker City Daily | 27 May 1876 | 3 | Purchase | ||
| OVERY | Joseph | 13 | Parker City Daily | 22 Sep 1875 | 3 | Wells | St. Joe | |
| OVERY | Joseph | 13 | Parker City Daily | 27 Jan 1876 | 3 | Elected | Millerstown | |
| OVERY | Joseph | 14 | Parker City Daily | 13 Jun 1876 | 3 | Oil Well | St. Joe | X |
| OWEN | Robert | 14 | Connoquenessing Valley News | 29 Jan 1880 | 1 | Harmonists | Harmony | |
| OWENS | A. | 4 | Butler Intelligencer | 22 Feb 1840 | 4 | Co. Treas. Report | Land Sold, Venango | |
| OWENS | Brice | 15 | Connoquenessing Valley News | 25 Jul 1889 | 2 | New House | ||
| OWENS | Ida | 16 | The Democratic Herald | 25 Mar 1898 | 7 | Land Transfers | Mars | X |
| OWENS | John F. | 14 | Parker City Daily | 01 Jun 1876 | 3 | Cemetery Inscription | Warren | |
| OWENS | M. | 4 | Butler Intelligencer | 07 Mar 1840 | 5 | Public Notice | Venango Township | |
| OWENS | R. J. | 9 | Union Herald | 11 Apr 1866 | 3 | Election | Adams | |
| OWENS | Robt D. | 14 | Connoquenessing Valley News | 22 May 1879 | 2 | Socialism | Harmony | |
| OWENS | S. D. | 13 | Parker City Daily | 24 Sep 1875 | 3 | Geography | ||
| OWENS | W. J. | 15 | Connoquenessing Valley News | 14 Aug 1884 | 3 | Roll of Honor | Valencia | |
| OWNERS | Thomas | 13 | Parker City Daily | 21 Oct 1875 | 3 | Contractor | ||
| OWZER | T | 11 | The Democratic Herald | 29 Mar 1871 | 3 | Murderer | X | |
| OXENBAUGH | Rachel | 2 | Butler Sentinel | 03 May 1828 | 3 | Marriage | Centrey Twp. | |
| OXFORD | J. W. | 13 | Parker City Daily | 22 Nov 1875 | 3 | Died | Corry | |
| OZENBAUGH | Isaac | 1 | The Butler Centinel | 08 Jan 1822 | 3 | List of Letters | Butler | X |
| OZENHAUGHER | Jacob | 2 | Butler Sentinel | 17 June 1826 | 3 | Sheriff's Sales | Clearfield Twp. | X |
| OZMER | Abraham | 2 | The Repository | 02 July 1836 | 3 | Unclaimed Letter | Butler Borough | |