Grafton is a town in Grafton County, New Hampshire, United States. The population was 1,340 at the 2010 census.
Originally granted in 1761, and re-granted in 1769, Grafton, like the county it resides in, takes its name from Augustus FitzRoy, 3rd Duke of Grafton, a relative of colonial governor Benning Wentworth. Grafton was incorporated in 1778.
Historically, Grafton's economic base consisted of subsistence farming, small-scale industry, and mining. Several mica mines and granite quarries once dotted the town's landscape, most notably Ruggles Mine.
According to the United States Census Bureau, the town has a total area of 42.6 square miles (110.3 km2), of which 41.7 square miles (108.0 km2) is land and 0.9 square miles (2.3 km2) is water, comprising 2.19% of the town. The highest point in Grafton is the summit of Melvin Mountain, at 2,177 feet (664 m) above sea level. Grafton Pond is in the western part of town. Grafton lies mostly within the Merrimack River watershed, though the western edge of town is in the Connecticut River watershed.
As of the census of 2010, there were 1,340 people, 564 households, and 372 families residing in the town. The population density was 32.1 people per square mile (12.4/km2). There were 839 housing units at an average density of 20.1 per square mile (7.8/km2).