Pennsylvania Counties by Population (2025)

There are 67 counties in Pennsylvania.

Largest Counties

Two counties in Pennsylvania have populations of more than one million:

• Philadelphia County, which is coterminous with Philadelphia and has a population of 1,574,765 (even though it is the second smallest county in the state by land area)
• Allegheny County with 1,227,553 residents

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%.

Other counties with substantial populations include:

• Montgomery County (820,656)
• Bucks County (626,751)
• Delaware County (563,995)

These are all in the top five most populous counties in the state, and census statistics show that each has had population increases of between 0.21% and 2.46% in recent years.

Smallest Counties

Many counties in Pennsylvania have populations of fewer than fifty thousand residents, including:

• Forest County (7,306)
• Juniata County (24,475)
• Susquehanna County (41,238)

The least populous county is Cameron County, with just 4,683 residents and a population decrease of 7.69% since the last census.

Population Changes

In general, the population increases in Pennsylvania‘s counties are fairly modest. None have increased by more than 6%, with the largest growth in:

• Cumberland County (5.09%)
• Centre County (5.06%)

Notable population decreases include:

• Cameron County (-7.69%)
• Cambria County (-6.37%, population reduced to 134,313)