Belvidere is a city in Boone County, Illinois, United States. It is the county seat of Boone County. Belvidere is part of the Rockford, Illinois Metropolitan Statistical Area. According to the United States Census Bureau, the city has a total area of 9.1 square miles (24km2), of which, 9.1 square miles (24km2) of it is land and 0.1 square miles (0.26km2) of it (0.55%) 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.