| View |
Creation |
Saint Clair, Township of (Allegheny, defunct) |
Division |
1838 |
| View |
Reduction |
Baldwin, Township of |
Creation |
Feb 24, 1844 |
| View |
Reduction |
South Pittsburgh, Borough of (defunct) |
Creation |
Mar 17, 1848 |
| View |
Reduction |
East Birmingham, Borough of (defunct) |
Creation |
May 18, 1849 |
| View |
Reduction |
Chartiers, Township of (Allegheny, defunct) |
Creation |
Apr 12, 1851 |
| View |
Expansion |
Scott, Township of (Allegheny) |
Reduction |
Mar 7, 1862 |
| View |
Reduction |
Scott, Township of (Allegheny) |
Expansion |
Mar 7, 1862 |
| View |
Reduction |
Mount Washington, Borough of (defunct) |
Creation |
Apr 12, 1866 |
| View |
Reduction |
Ormsby, Borough of (defunct) |
Creation |
Sep 8, 1868 |
| View |
Expansion |
Mount Washington, Borough of (defunct) |
Reduction |
Mar 1, 1869 |
| View |
Reduction |
Mount Washington, Borough of (defunct) |
Expansion |
Mar 24, 1869 |
| View |
Reduction |
Allentown, Borough of (Allegheny, defunct) |
Creation |
Mar 12, 1870 |
| View |
Reduction |
Saint Clair, Borough of (Allegheny, 1870-1873, defunct) |
Creation |
Sep 8, 1870 |
| View |
Reduction |
Beltzhoover, Borough of (defunct) |
Creation |
Jun 9, 1875 |
| View |
Expansion? |
Union, Township of (Allegheny, defunct) |
Reduction? |
1876 |
| View |
Reduction |
Baldwin, Township of |
Expansion |
1875–1876 |
| View |
Reduction? |
Union, Township of (Allegheny, defunct) |
Expansion? |
1876 |
| View |
Reduction |
West Liberty, Borough of (Allegheny, defunct) |
Creation |
Mar 7, 1876 |
| View |
Reduction |
Knoxville, Borough of (Allegheny, defunct) |
Creation |
Sep 14, 1877 |
| View |
Reduction |
Baldwin, Township of |
Expansion |
May 6, 1892 |
| View |
Reduction |
Mount Oliver, Borough of |
Creation |
Nov 9, 1892 |
| View |
Reduction |
Knoxville, Borough of (Allegheny, defunct) |
Expansion |
Feb 19, 1900 |
| View |
Reduction |
Mount Oliver, Borough of |
Expansion |
May 9, 1904 |
| View |
Reduction |
Saint Clair, Borough of (Allegheny, 1906-1923, defunct) |
Creation |
Dec 29, 1906 |
| View |
Dissolution |
Pittsburgh, City of |
Expansion |
Feb 15, 1924 |
