Newmarket is a town in Rockingham County, New Hampshire, United States. The population was 8,936 at the 2010 census. Some residents are students and employees at the nearby University of New Hampshire in Durham.The primary settlement in town, where 5,297 people resided at the 2010 census, is defined as the Newmarket census-designated place, or CDP, and is located at the junction of New Hampshire routes 108 and 152, adjacent to the Lamprey River.HistoryIncorporated in 1727, Newmarket is one of six towns granted by Massachusetts in the last year of the reign of King George I. It started as a parish of Exeter, and was granted full town privileges by the legislature in 1737. It was probably named for Newmarket in Suffolk, England. The Lamprey River, running through the town, was named for John Lamprey, an early settler. For a while, the town was called Lampreyville. Newmarket was a center of the New England shipping trade with the West Indies, including importation of sugar and African slaves.