1810
| RANK | COUNTY | TOTAL POPULATION | RANK | COUNTY | TOTAL POPULATION | |
| 1 | Philadelphia County | 111,210 | 19 | Adams County | 15,152 | |
| 2 | Lancaster County | 53,927 | 14 | Allegheny County | 25,317 | |
| 3 | Berks County | 43,146 | 32 | Armstrong County | 6,143 | |
| 4 | Chester County | 39,596 | 23 | Beaver County | 12,168 | |
| 5 | Northampton County | 38,145 | 18 | Bedford County | 15,746 | |
| 6 | Northumberland County | 36,327 | 3 | Berks County | 43,146 | |
| 7 | Washington County | 36,289 | 8 | Bucks County | 32,371 | |
| 8 | Bucks County | 32,371 | 29 | Butler County | 7,346 | |
| 9 | York County | 31,958 | 36 | Cambria County | 2,117 | |
| 10 | Dauphin County | 31,883 | 27 | Centre County | 10,681 | |
| 11 | Montgomery County | 29,703 | 4 | Chester County | 39,596 | |
| 12 | Cumberland County | 26,757 | 38 | Clearfield County | 875 | |
| 13 | Westmoreland County | 26,392 | 31 | Crawford County | 6,178 | |
| 14 | Allegheny County | 25,317 | 12 | Cumberland County | 26,757 | |
| 15 | Fayette County | 24,714 | 10 | Dauphin County | 31,883 | |
| 16 | Franklin County | 23,083 | 21 | Delaware County | 14,734 | |
| 17 | Luzerne County | 18,109 | 34 | Erie County | 3,758 | |
| 18 | Bedford County | 15,746 | 15 | Fayette County | 24,714 | |
| 19 | Adams County | 15,152 | 16 | Franklin County | 23,083 | |
| 20 | Huntingdon County | 14,778 | 22 | Greene County | 12,544 | |
| 21 | Delaware County | 14,734 | 20 | Huntingdon County | 14,778 | |
| 22 | Greene County | 12,544 | 30 | Indiana County | 6,214 | |
| 23 | Beaver County | 12,168 | 40 | Jefferson County | 161 | |
| 24 | Mifflin County | 12,132 | 2 | Lancaster County | 53,927 | |
| 25 | Somerset County | 11,284 | 17 | Luzerne County | 18,109 | |
| 26 | Lycoming County | 11,006 | 26 | Lycoming County | 11,006 | |
| 27 | Centre County | 10,681 | 41 | McKean County | 142 | |
| 28 | Mercer County | 8,277 | 28 | Mercer County | 8,277 | |
| 29 | Butler County | 7,346 | 24 | Mifflin County | 12,132 | |
| 30 | Indiana County | 6,214 | 11 | Montgomery County | 29,703 | |
| 31 | Crawford County | 6,178 | 5 | Northampton County | 38,145 | |
| 32 | Armstrong County | 6,143 | 6 | Northumberland County | 36,327 | |
| 33 | Wayne County | 4,125 | 1 | Philadelphia County | 111,210 | |
| 34 | Erie County | 3,758 | 42 | Potter County | 29 | |
| 35 | Venango County | 3,060 | 25 | Somerset County | 11,284 | |
| 36 | Cambria County | 2,117 | 37 | Tioga County | 1,687 | |
| 37 | Tioga County | 1,687 | 35 | Venango County | 3,060 | |
| 38 | Clearfield County | 875 | 39 | Warren County | 827 | |
| 39 | Warren County | 827 | 7 | Washington County | 36,289 | |
| 40 | Jefferson County | 161 | 33 | Wayne County | 4,125 | |
| 41 | McKean County | 142 | 13 | Westmoreland County | 26,392 | |
| 42 | Potter County | 29 | 9 | York County | 31,958 |