The Penn State Data Center provided these county and demographic data based on the 2020 Census data that were just release.
Pennsylvania grew by 2.4% over the last decade
Between 2010 and 2020, Pennsylvania’s population grew from 12,702,379 to 13,002,700, an increase of 300,321 or 2.4%. Over this same period, 44 Pennsylvania counties lost population and 23 grew.
Philadelphia County is still the largest county in the state
Philadelphia county is the most populous county in Pennsylvania, with a 2020 Census population of 1,603,797, an increase of 5.1% since 2010. The second largest county remains Allegheny County with 1,250,578 people, an increase of 2.2% since 2010. The five largest counties in Pennsylvania remained the same in 2020 as they were in 2010:
- Philadelphia: 1,603,797
- Allegheny: 1,250,578
- Montgomery: 856,553
- Bucks: 646,538
- Delaware: 576,830
Four of the top five counties grew faster than the state. Only Allegheny grew at a slower rate than the state overall. Philadelphia dropped from the fifth to the sixth largest city in the country in 2020, with Phoenix Arizona moving up to fifth.
Cameron County remains the least populous county in Pennsylvania
The five smallest Pennsylvania counties in 2020 are the same as in 2010:
- Cameron: 4,547
- Sullivan: 5,840
- Forest: 6,973
- Fulton: 14,556
- Potter: 16,396
All of these counties had population losses over the decade. Cameron saw the largest percent decline (10.6%) , while Potter had the largest numeric decline among the group (1,061).
Fasting-growing counties in Pennsylvania:
After a decade of population estimates suggesting that Lancaster County was among the top five fastest-growing counties, Montgomery and Dauphin counties grew at a faster rate according to today’s results. Only Cumberland County grew at a rate above 10%. The five fastest-growing counties in Pennsylvania from 2010-2020 were:
- Cumberland: 10.2%
- Lebanon: 7.3%
- Lehigh: 7.2%
- Chester: 7.1%
- Montgomery: 7.1%
Largest population losses in Pennsylvania counties
44 counties in Pennsylvania lost population over the decade. The counties with the largest numeric declines were:
- Westmoreland: -10,506
- Cambria: -10,207
- Erie: -9,690
- Fayette: -7,802
- Mercer: -5,986
The racial/ethnic composition of Pennsylvania in 2020 (from largest to smallest)
- White: 75.0%
- Black: 10.9%
- Hispanic: 8.1%
- Multiracial: 6.0%
- Asian: 3.9%
- Some other race: 3.9%
- American Indian and Alaska Native: 0.2%