Created in 1804 and named in honor of a former Pennsylvania Governor and Declaration of Independence signer.
Created on April 11, 1848, from part of Jefferson County and named for the woodlands contained within its limits.
Created in 1804 from parts of Huntingdon and Lycoming Counties and most likely name for the many clean fields formed by the bison herds of prior Native American tribes.
Created on March 9, 1771, from part of Cumberland County and named in honor of a fort.
Created on February 26, 1846, from parts of Huntingdon and Bedford Counties and named after a farmer, businessman, and state legislator that lobbied for the establishment of the county.
Created on September 24, 1788, from parts of Washington and Westmoreland counties and was Pennsylvania's first county to bear a Native American name.
Established on March 26, 1804, from part of Lycoming County named for the third President of the U.S.
Created on March 12, 1800, from part of Allegheny County and named for a colonel who worked as a western land agent for George Washington.
Formed in 1800 from parts of Allegheny and Lycoming counties and named after a Revolutionary Wary general killed at the Battle of Bunker Hill.
Created on February 26, 1846, from parts of Huntingdon and Bedford Counties and named after a farmer, businessman, and state legislator that lobbied for the establishment of the county.
Created on April 18, 1843, from parts of Jefferson, Clearfield, and McKean Counties, and is named for a large herd animal that historically inhabited the region.
Created on March 12, 1800, from parts of Allegheny and Lycoming Counties and the name "Venango" comes from the Native American name of the region, Onenge, meaning Otter.
Created in 1800 from part of Allegheny County and named for one of the Great Lakes.
Formed on March 11, 1839, from parts of Venango and Armstrong Counties and the home of Cook Forest State Park.
Created on March 26, 1804, from parts of Bedford, Huntingdon, and Somerset Counties and named for the nation of Wales in Latin.