The Gowanus Canal is a 1.8-mile-long (2.9 km) canal in the New York City borough of Brooklyn, on the westernmost portion of Long Island. Once a vital cargo transportation hub, the canal has seen decreasing use since the mid-20th century as domestic shipping declined. It continues to be used for occasional movement of goods and daily navigation of small boats, tugs, and barges. It is among the most polluted bodies of water in the United States.