Manchester is the most populous city in the U.S. state of New Hampshire. Located on the banks of the Merrimack River, it had a population of 115,644 at the 2020 census. Manchester is the tenth-most populous city in New England. Along with the city of Nashua, it is one of two seats of New Hampshire's most populous county, Hillsborough County. The Manchester–Nashua metropolitan area has approximately 423,000 residents and lies near the northern end of the Northeast megalopolis.