Belvidere is a town in Warren County, New Jersey, United States. As of the 2010 United States Census, the town's population was 2,681, reflecting a decline of 90 from the 2,771 counted in the 2000 Census, which had in turn increased by 102 from the 2,669 counted in the 1990 Census. It is the county seat of Warren County. Belvidere is located in the eastern section of the Lehigh Valley.Belvidere was incorporated as a town by an act of the New Jersey Legislature on April 7, 1845, from portions of Oxford Township, based on the results of a referendum held that day. The town's name means "beautiful to see" in Italian.