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 (-3.2%) from the 2,771 counted in the 2000 Census, which had in turn increased by 102 (+3.8%) 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.
According to the United States Census Bureau, the town had a total area of 1.48 square miles (3.84 km2), including 1.45 square miles (3.75 km2) of land and 0.04 square miles (0.09 km2) of water (2.36%).
Dildine Island is located in the Delaware River, approximately 4 miles (6.4 km) north of Belvidere.
Belvidere borders White Township in Warren County and Northampton County in Pennsylvania across the Delaware River.
The 2010 United States Census counted 2,681 people, 1,054 households, and 682 families in the town. The population density was 1,847.0 inhabitants per square mile (713.1/km2). There were 1,140 housing units at an average density of 785.4 per square mile (303.2/km2). The racial makeup was 96.01% (2,574) White, 1.57% (42) Black or African American, 0.11% (3) Native American, 0.78% (21) Asian, 0.00% (0) Pacific Islander, 0.22% (6) from other races, and 1.31% (35) from two or more races.