The Hudson River is a 315-mile (507 km) river that flows from north to south largely through eastern New York state. It originates in the Adirondack Mountains at Henderson Lake in the town of Newcomb, and flows south to New York Bay, a tidal estuary between New York and Jersey City, before draining into the Atlantic Ocean. The river marks boundaries between several New York counties and the eastern border between the U.S. states of New York and New Jersey. The lower half of the river is a tidal estuary, deeper than the body of water into which it flows, occupying the Hudson Fjord, an inlet that formed during the most recent period of North American glaciation, estimated at 26,000 to 13,300 years ago. Even as far north as the city of Troy, the flow of the river changes direction with the tides.
The Hudson River runs through the Munsee, Lenape, Mohican, Mohawk, and Haudenosaunee homelands. Prior to European exploration, the river was known as the Mahicannittuk by the Mohicans, Ka'nón:no by the Mohawks, and Muhheakantuck by the Lenape. The river was subsequently named after Henry Hudson, an Englishman sailing for the Dutch East India Company who explored it in 1609, and after whom Hudson Bay in Canada is also named. It had previously been observed by Italian explorer Giovanni da Verrazzano 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, and they called the present-day Delaware River the South River, which formed the spine of the Dutch colony of New Netherland. Settlements 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.