The following is a list of the 67 counties of the U.S. state of Pennsylvania.

The city of Philadelphia is coterminous with Philadelphia County, the municipalities having been consolidated in 1854, and all remaining county government functions having been merged into the city after a 1951 referendum.

[1][2] Eight of the ten most populous counties are in the southeastern portion of the state, including four out of the top five, and eight of the top ten most populous counties are in either the Greater Philadelphia or Greater Pittsburgh Metropolitan Statistical Areas.

The Federal Information Processing Standard (FIPS) code, used by the U.S. government to uniquely identify counties, is provided with each entry.

[3] The Province of Pennsylvania's Three Lower Counties had been transferred from New York Colony in 1682.