This is the first time that Allegheny County has added population in the decennial census since 1960. The growth rate for the county was about 2.2%, which is still relatively small compared to other large counties in the U.S.
The city of Pittsburgh lost population again. Compared to the 2010 Census, Pittsburgh shed 2,733 residents. However, many experts expected Pittsburgh to drop below 300,000 residents, but the 2020 Census showed that the city remained safely above that level at 302,971 residents. Pittsburgh's recent decline is also very small compared to the population loss between 2000 and 2010. That decade the city shrunk by 8.5%, But between 2010 to 2020, the city only shrunk by less than 1%.
The biggest growth rate among municipalities in Allegheny County was Ohio Township, which grew by more than 50%. The biggest loss rate among Allegheny County municipalities was West Elizabeth, which shrunk more than 22%. South Fayette Township saw an impressive raw gain of nearly 4,000 residents, according to Pittsburgh data analyst Ben Forstate.
The entire seven county Pittsburgh metro area — which includes Allegheny, Armstrong, Beaver, Butler, Fayette, Washington, and Westmoreland counties — increased up to 2,370,930. However the growth rate compared to 2010 was very small, an increase of 0.6%.
Adams: 101,407 to 103,852 (+2,445)— Jonathan Lai 🙊 賴柏羽 (@Elaijuh) August 12, 2021
Allegheny: 1,223,348 to 1,250,578 (+27,230)
Armstrong: 68,941 to 65,558 (-3,383)
Beaver: 170,539 to 168,215 (-2,324)
Bedford: 49,762 to 47,577 (-2,185)
Berks: 411,442 to 428,849 (+17,407)
Blair: 127,089 to 122,822 (-4,267)
Other Pittsburgh area counties to see population growth were Butler and Washington counties, with Butler County leading the way with a 5.3% growth rate. Butler County added 9,901 residents and now has 193,763 residents, according to the 2020 Census. Washington County grew much slower, but still added 1,529 residents, and is now home to 209,349.
Every other county in the Pittsburgh region lost population, led by Westmoreland County, which shed more than 10,000 residents since 2010. Fayette, Beaver, and Armstrong also saw substantial losses.