| Counties | 1998 | 1994 | 1990 | 1986 | 1982 | 1978 | 1974 | 1970 | 1966 | 1962 | 1958 | 1954 | 1950 | 1946 | 1942 | 1938 | 1934 | 1930 | 1926 | 1922 | % R Wins |
| Adams | R | R | D | R | R | R | R | R | R | R | R | D | R | R | R | R | D | R | R | D | 0.8 |
| Allegheny | R | D | D | D | R | D | D | D | D | R | D | D | D | R | D | D | D | R | R | R | 0.35 |
| Armstrong | R | R | D | D | D | D | D | D | R | R | R | D | R | R | R | R | R | R | R | R | 0.65 |
| Beaver | R | D | D | D | D | D | D | D | D | R | D | D | D | R | R | R | D | R | R | R | 0.4 |
| Bedford | R | R | D | R | R | R | R | R | R | R | R | D | R | R | R | R | D | R | R | D | 0.8 |
| Berks | R | R | D | R | R | R | D | D | R | R | D | D | D | R | D | R | D | D | R | D | 0.5 |
| Blair | R | R | D | R | R | R | R | D | R | R | R | R | R | R | R | R | D | R | R | R | 0.85 |
| Bradford | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Bucks | R | R | D | R | R | R | D | D | R | R | R | R | R | R | R | R | R | R | R | R | 0.85 |
| Butler | R | R | D | R | R | D | R | D | R | R | R | R | R | R | R | R | D | R | R | R | 0.8 |
| Cambria | R | D | D | D | D | D | D | D | R | R | D | D | D | R | D | R | D | R | R | R | 0.4 |
| Cameron | R | R | D | R | R | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | 0.9 |
| Carbon | R | R | D | D | D | R | D | D | R | R | D | D | D | R | R | R | D | R | R | D | 0.5 |
| Centre | R | R | D | R | R | R | R | D | R | R | R | R | R | R | R | R | D | R | R | D | 0.8 |
| Chester | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Clarion | R | R | D | R | R | D | R | D | R | R | R | R | R | R | R | R | D | R | R | D | 0.75 |
| Clearfield | R | R | D | D | D | D | D | D | R | R | R | D | R | R | R | R | D | R | R | R | 0.6 |
| Clinton | R | R | D | D | D | R | D | D | R | R | R | D | R | R | R | R | R | R | R | D | 0.65 |
| Columbia | R | R | D | D | D | R | D | R | R | R | R | D | D | R | D | R | D | R | R | D | 0.55 |
| Crawford | R | R | D | R | R | R | R | D | R | R | R | R | R | R | R | R | R | R | R | D | 0.85 |
| Cumberland | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | D | R | R | D | 0.85 |
| Dauphin | R | R | D | R | D | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.85 |
| Delaware | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Elk | R | R | D | D | D | D | R | D | D | R | D | D | D | R | D | R | D | R | R | R | 0.45 |
| Erie | R | R | D | R | R | R | R | D | D | R | R | D | R | R | R | R | D | D | R | R | 0.7 |
| Fayette | R | D | D | D | D | D | D | D | D | D | D | D | D | D | D | D | D | R | R | R | 0.2 |
| Forest | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Franklin | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | D | R | R | D | 0.85 |
| Fulton | R | R | D | R | R | R | D | D | R | R | D | D | D | D | R | R | D | R | R | D | 0.55 |
| Greene | R | D | D | D | D | D | D | D | D | D | D | D | D | D | D | D | D | R | R | D | 0.15 |
| Huntingdon | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | D | 0.9 |
| Indiana | R | R | D | D | R | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | 0.85 |
| Jefferson | R | R | D | R | R | D | R | R | R | R | R | R | R | R | R | R | D | R | R | R | 0.85 |
| Juniata | R | R | D | R | R | R | D | R | R | R | R | D | R | R | R | R | D | R | R | D | 0.75 |
| Lackawanna | R | D | D | D | D | R | D | D | D | D | D | D | D | R | D | D | R | R | R | R | 0.35 |
| Lancaster | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Lawrence | R | D | D | D | D | D | D | D | R | R | D | D | R | R | R | R | D | R | R | R | 0.5 |
| Lebanon | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Lehigh | R | R | D | R | R | R | D | D | R | R | R | D | R | R | R | R | D | D | R | D | 0.65 |
| Luzerne | R | D | D | D | D | R | D | D | D | R | D | D | R | R | R | R | R | R | R | R | 0.55 |
| Lycoming | R | R | D | R | D | R | R | R | R | R | R | D | R | R | R | R | D | R | R | D | 0.75 |
| McKean | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Mercer | R | R | D | D | D | D | R | D | R | R | R | D | R | R | R | R | D | R | R | R | 0.65 |
| Mifflin | R | R | D | R | R | R | D | R | R | R | R | D | R | R | R | R | D | R | R | D | 0.75 |
| Monroe | R | R | D | R | R | R | R | D | R | R | R | D | R | R | R | R | D | D | R | D | 0.7 |
| Montgomery | R | R | R | R | R | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Montour | R | R | D | D | R | R | R | R | R | R | R | D | R | R | R | R | D | D | R | D | 0.7 |
| Northhampton | R | R | D | D | R | R | D | D | D | R | D | D | D | D | R | R | D | D | R | D | 0.4 |
| Northhumberland | R | R | D | D | D | R | D | D | R | R | R | D | R | R | R | R | D | R | R | D | 0.6 |
| Perry | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | D | 0.9 |
| Phileldelphia | D | D | D | D | D | D | D | D | D | D | D | D | D | R | R | R | R | D | R | R | 0.3 |
| Pike | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | D | R | R | D | 0.85 |
| Potter | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | D | 0.9 |
| Schuylkill | R | R | D | D | D | R | D | D | R | R | R | R | R | R | R | R | D | R | R | D | 0.65 |
| Snyder | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | D | 0.9 |
| Somerset | R | R | D | D | R | D | R | R | R | R | R | D | R | R | R | R | R | R | R | R | 0.8 |
| Sullivan | R | R | D | R | R | R | R | R | R | R | R | D | R | R | R | R | R | R | R | D | 0.85 |
| Susquehanna | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Tioga | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Union | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | D | 0.9 |
| Venango | R | R | D | R | R | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | 0.9 |
| Warren | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Washington | R | D | D | D | D | D | D | D | D | D | D | D | D | D | D | D | D | R | R | R | 0.2 |
| Wayne | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | 0.95 |
| Westmoreland | R | D | D | D | D | D | D | D | D | R | D | D | D | D | D | D | D | R | R | R | 0.25 |
| Wyoming | R | R | D | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | R | D | 0.9 |
| York | R | R | D | R | R | R | D | D | R | R | D | D | D | D | R | R | D | R | R | D | 0.55 |
| Sate Wide | R | R | D | D | R | R | D | D | R | R | D | D | R | R | R | R | D | R | R | R | 0.65 |