The Hudson River is a 315-mile (507 km) river that flows from north to south primarily through eastern New York in the United States. The river originates in the Adirondack Mountains of Upstate New York, flows through the Hudson Valley, and eventually drains into the Atlantic Ocean, between New York City and Jersey City. The river serves as a political boundary between the states of New Jersey and New York, and further north between New York counties. The lower half of the river is a tidal estuary occupying the Hudson Fjord, which formed during the most recent period of North American glaciation, estimated at 26,000 to 13,300 years ago. Tidal waters influence the Hudson's flow from as far north as Troy.
The river is named after Henry Hudson, an Englishman sailing for the Dutch East India Company, who explored it in 1609, and after whom Canada's Hudson Bay is also named. It had previously been observed by Italian explorer Giovanni da Verrazano sailing for King Francis I of France in 1524, as he became the first European known to have entered the Upper New York Bay, but he considered the river to be an estuary. The Dutch called the river the North River – with the Delaware River called the South River – and it formed the spine of the Dutch colony of New Netherland. Settlement of the colony clustered around the Hudson, and its strategic importance as the gateway to the American interior led to years of competition between the English and the Dutch over control of the river and colony.
During the eighteenth century, the river valley and its inhabitants were the subject and inspiration of Washington Irving, the first internationally acclaimed American author. In the nineteenth century, the area inspired the Hudson River School of landscape painting, an American pastoral style, as well as the concepts of environmentalism and wilderness. The Hudson was also the eastern outlet for the Erie Canal, which, when completed in 1825, became an important transportation artery for the early-19th-century United States.