Intracoastal Waterway, a marine navigational route made up of two separate systems: the Atlantic Intracoastal Waterway and the Gulf Intracoastal Waterway. The Atlantic Intracoastal Waterway originally began near Gloucester, Masssachusetts, but today begins in Norfolk, Virginia. It runs 1,329 miles (2,139 km) to Key West, Florida. The Gulf Intracoastal Waterway runs 1,180 miles (1,899 km) from Apalachee Bay, Florida, to Brownsville, Texas.

The Intracoastal Waterway is composed mostly of protected bays, sounds, and estuaries, and of dredged channels and canals. Long stretches of the waterway lie between offshore barrier islands and the mainland; some sections are part of the open sea. The Intracoastal Waterway is used mainly by pleasure craft and shallow-draft commercial vessels. Barge traffic is especially heavy along the Texas and Louisiana coasts.

The Intracoastal Waterway is maintained by the U.S. Army Corps of Engineers. Most of the work on the waterway has been done since the early 1930's.

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