Milford is a town in Hillsborough County, New Hampshire, United States, on the Souhegan River. The population was 15,115 at the 2010 census. It is the retail and manufacturing center of a six-town area known informally as the Souhegan Valley.The town center of Milford, where 8,835 people resided at the 2010 census, is defined as the Milford census-designated place, and is located at the junction of New Hampshire routes 13 and 101A.