This is less than a one percent fall in Allegheny County’s population, from 1,248,717 in 2020 to 1,238,090 in 2021.
Allegheny County had the second largest population in Pennsylvania in 2021.
The US Census Bureau found more than 73 percent of counties in the US saw a natural decrease in population in 2021. This is up from a 55.5 percent increase in 2020.
The Midwest suffered the most sustained population decreases, with many counties along the US East Coast and through the Rocky Mountains seeing increases.
The US population continues to grow, though at a slower rate than before.
Pennsylvania Counties By Population Change from 2020 to 2021
| County | 2020 Estimated Population | 2021 Estimated Population | % Change in Population From Year to Year |
|---|---|---|---|
| Pike County | 58,591 | 59,952 | 2.3% |
| Forest County | 6,952 | 7,032 | 1.2% |
| Cumberland County | 259,996 | 262,919 | 1.1% |
| Carbon County | 64,751 | 65,412 | 1% |
| Chester County | 534,645 | 538,649 | 0.7% |
| Wayne County | 51,101 | 51,431 | 0.6% |
| Monroe County | 168,248 | 169,273 | 0.6% |
| Sullivan County | 5,838 | 5,868 | 0.5% |
| York County | 456,389 | 458,696 | 0.5% |
| Montgomery County | 856,947 | 860,578 | 0.4% |
| Perry County | 45,821 | 45,986 | 0.4% |
| Schuylkill County | 142,777 | 143,264 | 0.3% |
| Adams County | 103,795 | 104,127 | 0.3% |
| Columbia County | 64,667 | 64,872 | 0.3% |
| Clinton County | 37,350 | 37,465 | 0.3% |
| Luzerne County | 325,057 | 326,053 | 0.3% |
| Dauphin County | 286,544 | 287,400 | 0.3% |
| Lehigh County | 374,504 | 375,539 | 0.3% |
| Franklin County | 155,874 | 156,289 | 0.3% |
| Northampton County | 312,855 | 313,628 | 0.2% |
| Butler County | 193,851 | 194,273 | 0.2% |
| Lancaster County | 552,597 | 553,652 | 0.2% |
| Lebanon County | 143,242 | 143,493 | 0.2% |
| Berks County | 428,694 | 429,342 | 0.2% |
| Washington County | 209,157 | 209,470 | 0.1% |
| Mifflin County | 46,073 | 46,136 | 0.1% |
| Wyoming County | 26,001 | 26,034 | 0.1% |
| Susquehanna County | 38,354 | 38,389 | 0.1% |
| Lackawanna County | 215,516 | 215,663 | 0.1% |
| Bradford County | 59,858 | 59,892 | 0.1% |
| Bucks County | 646,008 | 646,098 | 0% |
| Clarion County | 37,178 | 37,156 | -0.1% |
| Tioga County | 40,969 | 40,929 | -0.1% |
| Bedford County | 47,523 | 47,461 | -0.1% |
| Union County | 42,625 | 42,568 | -0.1% |
| Montour County | 18,115 | 18,087 | -0.2% |
| Fulton County | 14,549 | 14,523 | -0.2% |
| Northumberland County | 91,471 | 91,266 | -0.2% |
| Snyder County | 39,717 | 39,621 | -0.2% |
| Centre County | 157,929 | 157,527 | -0.3% |
| Westmoreland County | 353,998 | 353,057 | -0.3% |
| Indiana County | 83,116 | 82,886 | -0.3% |
| Huntingdon County | 44,030 | 43,889 | -0.3% |
| Mercer County | 110,333 | 109,972 | -0.3% |
| Lycoming County | 113,980 | 113,605 | -0.3% |
| Clearfield County | 80,394 | 80,082 | -0.4% |
| Somerset County | 73,917 | 73,627 | -0.4% |
| Lawrence County | 85,865 | 85,497 | -0.4% |
| Delaware County | 576,388 | 573,849 | -0.4% |
| Crawford County | 83,723 | 83,351 | -0.4% |
| Elk County | 30,927 | 30,783 | -0.5% |
| Erie County | 270,427 | 269,011 | -0.5% |
| Armstrong County | 65,445 | 65,093 | -0.5% |
| Potter County | 16,356 | 16,259 | -0.6% |
| Cambria County | 132,957 | 132,167 | -0.6% |
| Blair County | 122,518 | 121,767 | -0.6% |
| Juniata County | 23,451 | 23,297 | -0.7% |
| Beaver County | 167,732 | 166,624 | -0.7% |
| Venango County | 50,275 | 49,938 | -0.7% |
| Jefferson County | 44,431 | 44,114 | -0.7% |
| Allegheny County | 1,248,717 | 1,238,090 | -0.9% |
| Warren County | 38,480 | 38,134 | -0.9% |
| McKean County | 40,306 | 39,941 | -0.9% |
| Fayette County | 128,393 | 126,931 | -1.1% |
| Greene County | 35,813 | 35,369 | -1.2% |
| Cameron County | 4,519 | 4,459 | -1.3% |
| Philadelphia County | 1,601,005 | 1,576,251 | -1.5% |
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