Cresson is located in eastern Cambria County at (40.462631, -78.586319), atop the Eastern Continental Divide, the height of land between the Eastern Seaboard of the United States and the Ohio River valley. The Little Conemaugh River rises in Cresson, flowing southwest to form the Conemaugh River, which in turn flows to the Kiskiminetas River, then the Allegheny River, the Ohio River, and finally the Mississippi. The north side of Cresson, meanwhile, drains north to Clearfield Creek, a tributary of the West Branch of the Susquehanna River, leading to Chesapeake Bay. Blair Gap, at the eastern edge of the Allegheny Plateau and east of town, is the location of the Allegheny Portage Railroad National Historic Site, where the first railroad (a portage railway) crossed the Allegheny Mountains.