| County | Rank | Change (2020) ↓ | 2025 Pop. | 2020 Pop. |
|---|---|---|---|---|
| Pike County | 1 | 7.99% | 63,256 | 58,576 |
| Cumberland County | 2 | 7.39% | 279,479 | 260,254 |
| Chester County | 3 | 5.86% | 566,180 | 534,860 |
| Adams County | 4 | 4.7% | 108,681 | 103,802 |
| York County | 5 | 4.32% | 476,503 | 456,754 |
| Lehigh County | 6 | 4.26% | 390,438 | 374,493 |
| Northampton County | 7 | 3.94% | 325,134 | 312,810 |
| Montgomery County | 8 | 3.48% | 886,707 | 856,900 |
| Berks County | 9 | 3.33% | 442,950 | 428,693 |
| Perry County | 10 | 3.11% | 47,265 | 45,838 |
| Butler County | 11 | 3.06% | 200,017 | 194,069 |
| Dauphin County | 12 | 2.95% | 295,172 | 286,717 |
| Franklin County | 13 | 2.93% | 160,516 | 155,951 |
| Luzerne County | 14 | 2.65% | 333,849 | 325,222 |
| Lancaster County | 15 | 2.46% | 566,412 | 552,834 |
| Columbia County | 16 | 2.41% | 66,242 | 64,686 |
| Delaware County | 17 | 2.2% | 589,226 | 576,523 |
| Carbon County | 18 | 2.02% | 66,059 | 64,752 |
| Lebanon County | 19 | 1.95% | 146,092 | 143,292 |
| Sullivan County | 20 | 1.68% | 5,929 | 5,831 |
| Centre County | 21 | 1.61% | 160,523 | 157,987 |
| Schuylkill County | 22 | 1.51% | 145,114 | 142,959 |
| Clinton County | 23 | 1.34% | 37,878 | 37,377 |
| Bucks County | 24 | 1% | 652,637 | 646,190 |
| Lackawanna County | 25 | 0.79% | 217,246 | 215,538 |
| Bedford County | 26 | 0.55% | 47,844 | 47,580 |
| Wayne County | 27 | 0.55% | 51,434 | 51,155 |
| Washington County | 28 | 0.53% | 210,524 | 209,414 |
| Montour County | 29 | 0.25% | 18,177 | 18,132 |
| Juniata County | 30 | -0.26% | 23,422 | 23,483 |
| Indiana County | 31 | -0.43% | 82,796 | 83,153 |
| Bradford County | 32 | -0.43% | 59,698 | 59,958 |
| Snyder County | 33 | -0.47% | 39,555 | 39,742 |
| Mifflin County | 34 | -0.49% | 45,920 | 46,145 |
| Susquehanna County | 35 | -0.67% | 38,092 | 38,349 |
| Lycoming County | 36 | -0.82% | 113,190 | 114,130 |
| Tioga County | 37 | -0.9% | 40,649 | 41,017 |
| Philadelphia County | 38 | -1.02% | 1,584,483 | 1,600,788 |
| Westmoreland County | 39 | -1.1% | 350,450 | 354,339 |
| Monroe County | 40 | -1.11% | 166,465 | 168,326 |
| Clarion County | 41 | -1.22% | 36,746 | 37,198 |
| Erie County | 42 | -1.27% | 267,297 | 270,739 |
| Fulton County | 43 | -1.29% | 14,394 | 14,582 |
| Allegheny County | 44 | -1.29% | 1,233,490 | 1,249,671 |
| Union County | 45 | -1.35% | 42,081 | 42,655 |
| Beaver County | 46 | -1.39% | 165,524 | 167,864 |
| Wyoming County | 47 | -1.41% | 25,674 | 26,042 |
| Venango County | 48 | -1.67% | 49,516 | 50,357 |
| Northumberland County | 49 | -1.78% | 89,923 | 91,550 |
| Crawford County | 50 | -2.03% | 82,126 | 83,825 |
| Huntingdon County | 51 | -2.04% | 43,173 | 44,071 |
| Blair County | 52 | -2.14% | 120,044 | 122,664 |
| Lawrence County | 53 | -2.39% | 83,913 | 85,970 |
| McKean County | 54 | -2.4% | 39,434 | 40,405 |
| Mercer County | 55 | -2.52% | 107,761 | 110,548 |
| Somerset County | 56 | -2.67% | 72,035 | 74,014 |
| Potter County | 57 | -2.69% | 15,946 | 16,387 |
| Cambria County | 58 | -2.77% | 129,503 | 133,198 |
| Elk County | 59 | -2.95% | 30,027 | 30,939 |
| Jefferson County | 60 | -3.08% | 43,109 | 44,480 |
| Clearfield County | 61 | -3.17% | 77,883 | 80,431 |
| Armstrong County | 62 | -3.35% | 63,264 | 65,460 |
| Forest County | 63 | -3.56% | 6,716 | 6,964 |
| Warren County | 64 | -3.77% | 37,074 | 38,526 |
| Fayette County | 65 | -4.2% | 123,183 | 128,585 |
| Cameron County | 66 | -4.81% | 4,314 | 4,532 |
| Greene County | 67 | -6.8% | 33,427 | 35,867 |
Pennsylvania's counties show varied growth patterns from 2020 to 2025. Pike County leads with 7.99% annualized growth, followed by Cumberland County (7.39%) and Chester County (5.86%). The largest counties are Philadelphia County (1,584,483), Allegheny County (1,233,490), and Montgomery County (886,707). Of the 67 counties in Pennsylvania, 29 are growing while 38 have experienced population decline. Overall, counties averaged 0.05% annualized growth, with total population growing by 1.11% annually.
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