Pen Mar, PA

Pen Mar is a Franklin County census-designated place on the western slope of South Mountain, right on the Pennsylvania-Maryland line. The 2020 census counted 1,171 residents. Its name is a tidy joining of Pennsylvania and Maryland, and the border is more than a line on the map: the community continues south into Maryland under the same Pen Mar name. Pennsylvania Route 550 runs through the Pennsylvania side toward Rouzerville, making the mountain settlement's connection to the valley straightforward.

The best-known nearby gathering place is Pen Mar Park, just across the line in Washington County, Maryland. The park was selected as a resort site in 1871 and still has the pavilion tradition that grew from its old dance hall. High Rock and the ridge's hiking routes put the area into a much bigger mountain landscape, but Pen Mar's appeal is the way all those layers meet: a border name, a mountain road, a public park, and a community split between two states without losing its shared label.