Population of Counties in Pennsylvania (2018)

Two counties in 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 2018 Population Growth Since 2010
Philadelphia County1,580,8633.44%
Allegheny County1,223,048-0.07%
Montgomery County826,0753.13%
Bucks County628,3410.47%
Delaware County564,6961.04%
Lancaster County542,9034.34%
Chester County519,2933.88%
York County446,0782.45%
Berks County417,8541.42%
Lehigh County366,4944.66%
Westmoreland County352,627-3.43%
Luzerne County317,343-1.14%
Northampton County303,4051.83%
Dauphin County275,7102.79%
Erie County274,541-2.22%
Cumberland County250,0666.01%
Lackawanna County210,761-1.76%
Washington County207,298-0.30%
Butler County187,1081.64%
Monroe County168,046-1.08%
Beaver County166,140-2.64%
Centre County162,6605.43%
Franklin County154,2342.87%
Schuylkill County142,569-3.84%
Lebanon County139,7544.58%
Cambria County133,054-7.25%
Fayette County131,504-3.62%
Blair County123,457-2.81%
Lycoming County113,841-2.04%
Mercer County111,750-4.17%
Adams County102,3360.86%
Northumberland County92,029-2.44%
Lawrence County87,069-4.29%
Crawford County86,159-2.79%
Indiana County84,953-4.41%
Clearfield County79,685-2.24%
Somerset County74,501-4.22%
Columbia County65,932-2.10%
Armstrong County65,642-4.67%
Carbon County63,853-2.15%
Bradford County60,853-2.98%
Pike County55,691-2.98%
Venango County51,762-5.84%
Wayne County51,205-3.05%
Bedford County48,480-2.44%
Mifflin County46,388-0.53%
Perry County46,1270.32%
Huntingdon County45,491-1.17%
Union County44,595-0.88%
Jefferson County43,804-3.01%
McKean County41,330-4.62%
Susquehanna County40,985-5.51%
Snyder County40,8012.77%
Tioga County40,793-2.81%
Warren County39,659-5.07%
Clinton County38,998-0.63%
Clarion County38,458-3.68%
Greene County36,770-4.73%
Elk County30,197-5.18%
Wyoming County27,322-3.21%
Juniata County24,514-0.44%
Montour County18,272-0.19%
Potter County16,802-3.78%
Fulton County14,590-1.92%
Forest County7,297-5.37%
Sullivan County6,089-4.92%
Cameron County4,592-9.48%