From there the Salem River turns to the south, flowing along the boundary of Mannington and Pennsville Townships,[4] where it widens into a meandering shallow estuary, Kates Creek Meadow, and passes the city of Salem, its head of navigability.

[5] It flows into the Delaware River from the east near the head of Delaware Bay, on the boundary of Pennsville and Elsinboro townships, approximately 2 miles (3 km) west of Salem and approximately 5 miles (8 km) southeast of Finns Point.

The Delaware River Main Channel is maintained at a depth of 40 feet (12 m) and expected to be 45 feet (14 m) in 2017[6] Reach D, which includes the entrance to Port of Salem, was completed in 2010.

The river is entered though Salem Cove about 50 miles (80 km) from the entrance of the Delaware Bay.

Fort Elfsborg, a settlement of the New Sweden colony was constructed along the eastern bank of the Delaware near the mouth of the Salem in 1642–1643.