Hudson is a town in Hillsborough County, New Hampshire, United States. It is located along the Massachusetts state line. The population was 24,467 at the 2010 census, with an estimated population of 24,645 in 2013. It is the ninth-largest municipality (town or city) in the state, by population.

The primary settlement in town, where 7,336 people resided at the 2010 census, is defined as the Hudson census-designated place (CDP) and is located at the junctions of New Hampshire routes 102, 111 and 3A, directly across the Merrimack River from the city of Nashua.

Hudson began as part of the Dunstable Land Grant that encompassed the current city of Nashua, New Hampshire, and the towns of Dunstable and Pepperell, Massachusetts, as well as parts of other nearby towns on both sides of the border. In 1732, all of Dunstable east of the Merrimack River became the town of Nottingham, Massachusetts. Nine years later, the northern boundary of Massachusetts was finally officially established, and the New Hampshire portion of Nottingham became Nottingham West, to avoid confusion with Nottingham, New Hampshire to the northeast.

In 1830, after the better part of a century, the name was changed to "Hudson" to avoid confusion with the older town of Nottingham. The name apparently comes from an early belief that the Merrimack River had once been thought to be a tributary of the Hudson River, or that the area had once been explored by Henry Hudson; both proved to be entirely apocryphal stories, but the name of the town remains today.

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