The town was chartered by Massachusetts Governor Jonathan Belcher in 1735 as one in a line of nine forts intended to protect southwestern New Hampshire from Indian attack.

It was named for Johann Heinrich Alsted, who compiled an early encyclopedia that was popular at Harvard College.

It decided to join Vermont in April 1781, but at the insistence of George Washington, returned to New Hampshire authority early the next year.

Paper was then a rare and expensive product, made by chopping rags of linen and cotton cloth into pulp.

While Alstead was basically an agricultural community, its streams and ponds once powered a variety of small mills.

[7] Shedd-Porter Memorial Library, built in 1909–1910 in the Beaux-Arts style, was a gift to Alstead and Langdon by native son John G. Shedd, president of Marshall Field's department store in Chicago.

Another native son philanthropist, Charles M. Vilas, gave a large public recreation area, school building and the only carillon in Cheshire County.

The storm created major property damage in Alstead, Langdon, and Walpole along the Cold River and Warren Brook.

A Save Our History grant from The History Channel provided funding to the Alstead Historical Society and several students of the local high school, who wrote and printed a book called Too Much Water, Too Much Rain,[9] chronicling the disaster and its aftermath.