1850 Counties of Pennsylvania
| in area | Courts held at | Pop in 1850 | ||
| Adams Co, PA | southern part | 360 sq miles | Gettysburgh | 25,981 |
| Alleghany Co, PA | south west part, water by Alleghany, Youghiogheny, Monongabia & Ohio rivers | 575 sq miles | Pittsburgh | 138,300 |
| Armstrong Co, PA | western part, water by Alleghany river | 700 sq miles | Kittaning | 29,560 |
| Beaver Co, PA | in western side, crossed by Ohio & Beaver rivers | 600 sq miles | Beaver | 26,689 |
| Bedford Co, PA | on southern boundary, drained by Juniata & Potomac rivers | 1,600 sq miles | Bedford | 23,052 |
| Berks Co, PA | in Southeastern side | 1,020 sq miles | Reading | 77,129 |
| Blair Co, PA | central part, crossed by Frankstown branch of Juniata River | 700 sq miles | Hollidaysburgh | 21,777 |
| Bucks Co, PA | easterly boundary, on west side of Delaware river | 600 sq miles | Doylestown | 56,091 |
| Butler Co, PA | western part | 840 sq miles | Butler | 30,346 |
| Cambria Co, PA | central part, drained by Connemaugh river | 720 | Ebensburgh | 17,773 |
| Carbon Co, PA | eastern part, crossed by Lehigh river | blank | Mauch Chunk | 15,686 |
| Centre Co, PA | central part, west branch Susquehanna river on NW | 1560 | Bellefonte | 23,355 |
| Chester Co, PA | southeast corner, Schuylkill river on NE | 729 | Westchester | 66,438 |
| Clearfield Co, PA | western part, crossed by west branch of Susquehanna river | 1425 | Clearfield | 12,586 |
| Clinton Co, PA | northern part, crossed by west branch of Susquehanna river | 840 | Lock Haven | 11,207 |
| Columbia Co, PA | central part, crossed by east branch Susquehanna river | 700 | Danville | 17,710 |
| Crawford Co, PA | west boundary | 1016 | Mendville | 37,849 |
| Cumberland Co, PA | southern part, Susquehanna river on northeast | 544 | Carlisle | 34,327 |
| Dauphin Co, PA | southeast part, Susquehanna river on the west | 608 | Harrisburgh (also State Capital) | 35,754 |
| Delaware Co, PA | southeast part, Delaware river on southeast | 220 | Chester | 24,679 |