[2] Situated at the northern edge of the White Mountains, Littleton is bounded on the northwest by the Connecticut River.

The main village in town, where 4,467 people lived at the 2020 census, is defined as the Littleton census-designated place (CDP) and is centered on the intersection of U.S. Route 302 with New Hampshire Route 116, along the Ammonoosuc River.

The land was later passed to the Apthorp family's associates from Newburyport, Massachusetts, headed by Colonel Moses Little.

Colonel Little held the post of Surveyor of the King's Woods, and the town was named in his honor when it was incorporated in 1784, the same year New Hampshire became a state.

Between 1867 and 1909, the local Kilburn Brothers factory published photographs and stereoviews, and sold stereoscopes, double-picture viewers popular in the Victorian age.

[1] The main village of Littleton, a census-designated place, has a total area of 8.6 square miles (22 km2), of which 0.12% is water.

As of January 2006 Littleton is also served by a public transportation bus route[13] connecting with Whitefield and Lancaster.