The Lehigh River is a 109-mile-long (175 km) tributary of the Delaware River in eastern Pennsylvania. The river flows in a generally southward pattern from the Pocono Mountains in Northeastern Pennsylvania through Allentown and much of the Lehigh Valley before joining the Delaware River in Easton.

The Delaware River is a major river in the Mid-Atlantic region of the United States and is the longest free-flowing (undammed) river in the Eastern United States. From the meeting of its branches in Hancock, New York, the river flows for 282 miles (454 km) along the borders of New York, Pennsylvania, New Jersey, and Delaware, before emptying into Delaware Bay.