Dixon is a city in Lee County, Illinois, United States. The population was 15,941 at the 2000 census. Named for its founder John Dixon, it is the county seat of Lee County. Located on the Rock River, Dixon was the boyhood home of former U.S. President Ronald Reagan. Dixon is also the site of the Lincoln Monument State Memorial, marking the spot where Abraham Lincoln joined the Illinois militia at Fort Dixon in 1832 during the Black Hawk War. The memorial is located on the west side of Dixon's main north-south street, Galena Avenue, (U.S. Highway 52 also U.S. 26), just north of the Rock River.