Petersburg is a borough in Huntingdon County, Pennsylvania, United States. It was a stop on the former Pennsylvania Railroad Main Line between Tyrone and Huntingdon and the junction point for the Petersburg Branch. The population was 480 at the 2010 census.

Huntingdon County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 44,092. Its county seat is Huntingdon. The county was created on September 20, 1787, mainly from the northern part of Bedford County, plus an addition of territory on the east from Cumberland County. The county is part of the Southwest Pennsylvania region of the state.