Tyler built mills using stone quarried from his land on nearby Mount Ascutney, and built Claremont's first mill on the Sugar River on the site of the Coy Paper Mill.
Large brick factories were built along the stream, including the Sunapee Mills, Monadnock Mills, Claremont Machine Works, Home Mills, Sanford & Rossiter, and Claremont Manufacturing Company.Principal products were cotton and woolen textiles, lathes and planers, and paper.Although like other New England mill towns, much industry moved away or closed in the 20th century, the city's former prosperity is evident in some fine Victorian architecture, including the 1897 city hall and opera house.Before colonial settlement, the Upper Connecticut River Valley was home to the Pennacook and Western Abenaki (Sokoki) peoples, later merging with members of other Algonquin tribes displaced by the wars and famines that accompanied the European settling of the region.The Hunter Archeological Site, located near the bridge connecting Claremont with Ascutney, Vermont, is a significant prehistoric Native American site that includes seven levels of occupational evidence, including evidence of at least three longhouses.
The oldest dates recorded from evidence gathered during excavations in 1967 were to AD 1300. Although first settled in 1762 by Moses Spafford and David Lynde, many of the proprietors arrived in 1767, with a large number from Farmington, Hebron and Colchester, Connecticut.The undulating surface of rich, gravelly loam made agriculture an early occupation. Samuel Ashley, who was given a charter to establish a ferry across the Connecticut River in 1784, the location of which is still known as Ashley's Ferry landing.Spafford was also the first man to marry in Claremont, and his son, Elijah, was the first white child to be born in the town.The Union Episcopal Church in West Claremont was built in 1773, and is the oldest surviving Episcopal church building in New Hampshire and the state's oldest surviving building built exclusively for religious purposes.The parish was organized in 1771 and chartered by the New Hampshire legislature in 1794 as Union Church Parish.In 1777, when the New Hampshire Grants declared their own sovereignty as the Vermont Republic, Claremont was one of sixteen New Hampshire towns inclined to join them, and made multiple attempts to do so.