The Delaware River is a major river on the Atlantic coast of the United States. The Delaware was explored by Adriaen Block as part of the New Netherlands Colony, and was named the South River to mark the southernmost reach of that colony.
The river meets tide-water at Trenton, New Jersey. Its total length, from the head of the longest branch to Cape May and Cape Henlopen, is 410 miles (660 km), and above the head of the Delaware Bay its length is 360 miles (579 km). The mean freshwater discharge of the Delaware River into the estuary is 11,550 cubic feet (330 m³) per second.
The Delaware River constitutes, in part, the boundary between Pennsylvania and New York, the entire boundary between New Jersey and Pennsylvania, and most of the boundary between Delaware and New Jersey. A historical oddity, the Delaware-New Jersey Border is actually at the eastern-most river shoreline within the Twelve-Mile Circle of New Castle, rather than the usual mid river or mid channel borders, causing small portions of the New Jersey peninsula falling west of the shoreline to fall under the jurisdiction of Delaware. The rest of the borders follow a mid-channel approach.
