Henniker is a town in Merrimack County, New Hampshire, United States. As of the 2020 census, the reported total population of the town was 6,185, although the figure, 27.9% greater than the 2010 population, has been questioned by local officials. Henniker is home to New England College and Pats Peak Ski Area. Henniker is a college town and reso…Henniker is a town in Merrimack County, New Hampshire, United States. As of the 2020 census, the reported total population of the town was 6,185, although the figure, 27.9% greater than the 2010 population, has been questioned by local officials. Henniker is home to New England College and Pats Peak Ski Area. Henniker is a college town and resort area, featuring both skiing and white-water kayaking.