Riverhead is a town in Suffolk County, New York, United States, on the north shore of Long Island. Since 1727, Riverhead has been the county seat of Suffolk County, though most county offices are in Hauppauge. As of the 2020 census, the population was 35,902. The town rests on the mouth of the Peconic River, from which it derives its name. The smaller hamlet of Riverhead lies within it, and is the town's principal economic center. The town is 166 miles (267 km) southwest of Boston via the Orient Point-New London Ferry, and is 76 miles (123 km) northeast of New York City.