Dalton is a town in Coös County, New Hampshire, United States. The population was 933 at the 2020 census. It is part of the Berlin, NH-VT Micropolitan Statistical Area. Dalton was incorporated in 1764 under the name "Chiswick", named for the Duke of Devonshire's castle. The name was changed to "Apthorp" in 1770, after the Apthorp family. In 1784 …Dalton is a town in Coös County, New Hampshire, United States. The population was 933 at the 2020 census. It is part of the Berlin, NH-VT Micropolitan Statistical Area. Dalton was incorporated in 1764 under the name "Chiswick", named for the Duke of Devonshire's castle. The name was changed to "Apthorp" in 1770, after the Apthorp family. In 1784 Apthorp was divided into two towns, Littleton and Dalton. The name "Dalton" was chosen in honor of Tristram Dalton, merchant and senator from Massachusetts.