Dorchester is a town in Grafton County, New Hampshire, United States.

Finally, it was regranted by Governor John Wentworth to 72 people on May 1, 1772, and settlement began soon thereafter.

The first settlers were Benjamin Rice and Stephen Murch from Hanover, but originally from Connecticut.

By 1859, when the population reached 711, there were eleven sawmills, in addition to several clapboard and shingle mills.

The northeastern half of town, which drains to the South Branch of the Baker, is part of the Merrimack River watershed, while the southwestern half is part of the Connecticut River watershed.

[5] The highest point in Dorchester is on its western boundary, where the elevation reaches 3,190 feet (970 m) above sea level, just east of the summit of Smarts Mountain.