The Pennsylvanian is the Upper Carboniferous epoch in the strata of North America. It comes after (above) the Mississippian, and before the Permian. The Pennsylvanian started about 323 million years ago (mya), and ended about 299 mya.

The coal measures, which give the Carboniferous its name, are the remains of peat formed by dense tropical wetland forests. They were formed in the Pennsylvanian, from about 315–300 million years years ago.