Hillsborough, frequently spelled Hillsboro, is a town in Hillsborough County, New Hampshire, United States. The population was 4,928 at the 2000 census. It includes Hillsborough Center; Hillsborough Upper Village; Hillsborough Lower Village; Emerald Lake Village; and the primary settlement in town, known either as "Bridge Village" or simply "Hillsborough". The town is home to Fox State Forest and part of Low State Forest. The Hillsborough CDP is a census-designated place that roughly encompasses the central urban area of the town, located at the junction of U.S. Route 202 and New Hampshire Routes 9 and 149. Over 37% of the town's population resides in the CDP.