Hudson is a town in Hillsborough County, New Hampshire, United States. It is located along the Massachusetts state line. The population was 25,394 at the 2020 census. It is the tenth-largest municipality in the state, by population.

Hillsborough County is the most populous county in the U.S. state of New Hampshire. As of the 2020 census, the population was 422,937, almost one-third the population of the entire state. Its county seats are Manchester and Nashua, the state's two biggest cities. Hillsborough is northern New England's most populous county as well as its most densely populated.