The Hudson River, originally called Muh-he-kun-ne-tuk in Mahican, is a river running mainly through New York State but partly forming the boundary between the states of New York and New Jersey. It is named for Henry Hudson, an Englishman sailing for the Netherlands, who explored it in 1609, though the first European to see it was the Italian Giovanni da Verrazano in 1524 whose expedition was financed by the citizens of Lyon, France, under the auspices of King Francois I. Early European settlement of the area clustered around the river.

View of the Hudson River with Jersey City, 1880s

The official source of the Hudson is Lake Tear-of-the-Clouds in the Adirondack Mountains. The Hudson is joined at Albany by the Mohawk River and flows south until it reaches the Atlantic Ocean between Manhattan Island and New Jersey, forming New York Harbor, at New York Bay, an arm of the Atlantic Ocean. The Hudson as it passes through New York City was also known as the North River.

The Hudson and its tributaries--notably the Mohawk River--drain a large area, and the river is navigable for a great distance. The Erie Canal, built early in the 19th century, connects the Hudson River to Lake Erie, enabling shipping between cities on the Great Lakes and Europe via the Atlantic Ocean.

The Hudson is sometimes called a "drowned" river, because the rising ocean after the most recent ice age brought salt water well above the mouth of the river. The lower part of the river near Manhattan is a tidal estuary, with strong tides making parts of New York Harbor difficult and dangerous to navigate. The old riverbed beyond the current shoreline, Hudson Canyon, is a rich fishing area.

The Hudson is crossed at numerous points by bridges and tunnels. The width of the river in its southern half required major feats of engineering to bridge, the results today visible in the Verrazano and George Washington Bridges, as well as the Lincoln and Holland Tunnels.