Population of Counties in Pennsylvania (2020)

Two counties in the state of Pennsylvania have populations of more than one million. These are Philadelphia County, which is coterminous with the city of Philadelphia and has a population of 1,574,765 (even though it is the second smallest county in the state by land area), and Allegheny County, with its 1,227,553 residents. As of 2018, both of these counties have grown their populations since the last census, with Philadelphia County increasing by 3.04% and Allegheny County by a more modest 0.30%.

A number of other counties in Pennsylvania, while not quite as large, still have substantial populations. Montgomery County (820,656), Bucks County (626,751), and Delaware County (563,995) are all in the top five most populous counties in the state, and census statistics show that each of these have also had population increases of between 0.21% and 2.46% in recent years. Conversely, many counties in Pennsylvania have populations of fewer than fifty thousand residents. These include Forest County (7,306), Juniata County (24,475), and Susquehanna County (41,238).

In general, the population increases in Pennsylvania's counties are fairly modest. None have increased by more than 6%, with Cumberland County topping the list at 5.09%, closely followed by Centre County at 5.06%. Quite a number of counties have had negative population growth: Cameron County, the least populous in the state, has just 4,683 residents and its population has decreased by 7.69% since the last census, while the larger Cambria County's population has reduced to 134,313, representing a 6.37% decrease.

Name 2020 Population Growth Since 2010
Philadelphia County1,591,9704.17%
Allegheny County1,214,040-0.81%
Montgomery County836,6884.47%
Bucks County630,5290.82%
Delaware County567,2791.48%
Lancaster County548,5635.43%
Chester County528,2705.67%
York County453,3754.13%
Berks County425,4083.25%
Lehigh County373,5586.68%
Westmoreland County347,191-4.92%
Luzerne County317,690-1.03%
Northampton County308,4693.54%
Dauphin County279,6294.23%
Erie County268,399-4.42%
Cumberland County255,7938.43%
Lackawanna County211,099-1.60%
Washington County207,446-0.23%
Butler County189,6563.02%
Monroe County172,3431.47%
Centre County163,9156.29%
Beaver County162,820-4.59%
Franklin County155,5313.75%
Lebanon County144,8108.36%
Schuylkill County140,869-5.00%
Cambria County129,082-10.02%
Fayette County128,469-5.84%
Blair County121,126-4.66%
Lycoming County113,132-2.67%
Mercer County108,947-6.57%
Adams County103,6992.19%
Northumberland County89,715-4.86%
Lawrence County85,248-6.32%
Indiana County83,745-5.76%
Crawford County83,613-5.64%
Clearfield County78,614-3.60%
Somerset County73,144-5.94%
Columbia County65,070-3.40%
Carbon County64,951-0.47%
Armstrong County64,037-7.01%
Bradford County60,523-3.53%
Pike County56,753-1.07%
Wayne County51,398-2.74%
Venango County50,152-8.77%
Bedford County47,652-4.09%
Perry County46,3530.93%
Mifflin County45,998-1.37%
Union County44,843-0.35%
Huntingdon County44,756-2.71%
Jefferson County43,267-4.20%
Tioga County40,887-2.59%
Snyder County40,4501.87%
McKean County40,246-7.15%
Susquehanna County39,817-8.14%
Warren County39,140-6.30%
Clarion County38,387-3.87%
Clinton County38,378-2.22%
Greene County35,820-7.23%
Elk County29,927-6.07%
Wyoming County26,376-6.60%
Juniata County24,8560.94%
Montour County18,170-0.72%
Potter County16,196-7.22%
Fulton County14,619-1.64%
Forest County7,215-6.38%
Sullivan County5,935-7.37%
Cameron County4,234-16.69%