Once called New Durham Gore because of the upland areas, or "gores", Alton was mainly settled by farmers because the higher areas provided less frost. Merchants then filled the lowlands. Early Alton history is filled with stories of the merchants trying to convince the farmers to incorporate.

In 1796 New Durham Gore was incorporated as Alton. Once a regular stop for steamboats, Alton is now a regular stop on the M/S Mount Washington cruise. In fact, Alton Bay is considered the birthplace of the Mount Washington Cruises, as the first side-wheeler was launched there in 1872.

Local lore includes a horse buried in the town cemetery. Old Tom, a Charger, was ridden by Major George D. Savage on the battlefields during the Civil War.