 The ridge peaks at 0.83 mile (1.33 km) NE from Perry County's southmost corner; it measures 2,269' (692m) ASL.The county is drained by the south-flowing Susquehanna River, which forms almost all of its eastern boundary.The Juniata River enters Perry County from Juniata County near Millerstown, and flows southeast to its confluence with the Susquehanna River near Duncannon.