Huntingdon, county, central Pennsylvania, U.S., consisting of a mountainous area in the Appalachian Ridge and Valley physiographic province located east of the city of Altoona. The principal waterways are Raystown Lake and the Juniata, Little Juniata, and Raystown Branch Juniata rivers, as well as Aughwick, Blacklog, and Tuscarora creeks. Natural features include Sideling Hill and Bald Eagle, Tussey, Tuscarora, Jacks, Shade, Stone, and Blacklog mountains. Parklands include Trough Creek, Greenwood Furnace, and Whipple Dam state parks.
The Oneida were among the Indian tribes who occupied the area when white settlers arrived in the mid-18th century. The county was created in 1787 and named for the evangelist Selina Hastings, countess of Huntingdon. The borough of Huntingdon is the county seat. The main economic activities are manufacturing, services, and retail trade. Area 875 square miles (2,267 square km). Pop. (2000) 45,586; (2010) 45,913.