Grafton County is a county located in the state of New Hampshire, in the United States. 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 Claremont-Lebanon, NH–VT Micropolitan Statistical Area.