Grafton County is a county located in the U.S. state of New Hampshire. As of the 2010 census, the population was 89,118. Its county seat is North Haverhill, which is a village within the town of Haverhill. Until 1972, the county courthouse and other offices were located in downtown Woodsville, a larger village within the town of Haverhill. Grafton County is part of the Lebanon, NH–VT Micropolitan Statistical Area.
The county is the home of Dartmouth College and Plymouth State University. Progressive Farmer rated Grafton County fourth in its list of the "Best Places to Live in Rural America" in 2006, citing low unemployment (despite slow economic growth), a favorable cost of living, and the presence of White Mountain National Forest, the state's only national forest.
Grafton was one of the five counties originally identified for New Hampshire in 1769. It was named for Augustus FitzRoy, 3rd Duke of Grafton, who had been a supporter of American causes in Parliament, and who was serving as British Prime Minister at the time. The county was organized at Woodsville in 1771, and originally included the entire northern frontier of New Hampshire, including a number of towns that are now in Vermont. In 1803, the northern area was removed for the formation of Coos County. The three counties to the south were Strafford, Hillsborough and Cheshire, and the eastern edge bordered the "District of Maine". In 1797, the county contained 50 townships and 17 locations, and had a population of 23,093.