Belvidere is a city in Boone County, Illinois, United States. The population was 25,585 as of the 2010 census. It is the county seat of Boone County. Belvidere is part of the Rockford, Illinois Metropolitan Statistical Area.
Belvidere is located at 42°15′17″N 88°50′39″W (42.254758, -88.844093), and sits approximately 800 feet (240 m) above sea level. Located in north central Illinois, Belvidere is approximately 75 miles (121 km) northwest of the downtown of Chicago, and approximately 12 miles (19 km) east of Rockford. Belvidere is divided by the Kishwaukee River.
According to the 2010 census, Belvidere has a total area of 12.312 square miles (31.89 km2), of which 12.08 square miles (31.29 km2) (or 98.12%) is land and 0.232 square miles (0.60 km2) (or 1.88%) is water. Belvidere is located in north central Illinois and is 75 miles from downtown Chicago on Routes 20, 76 and the Northern Illinois Toll road, with the Kishwaukee River dividing the town. Belvidere is an industrial community surrounded by prosperous farms.