Lee County is a county located in the U.S. state of Illinois. According to the 2020 census, it has a population of 34,145. Its county seat is Dixon.

Dixon is a city and the county seat of Lee County, Illinois, United States. The population was 15,274 as of the 2020 census. The city is named after founder John Dixon, who operated a rope ferry service across the Rock River, which runs through the city. The Illinois General Assembly designated Dixon as "Petunia Capital of Illinois" in 1999 and "The Catfish Capital of Illinois" in 2009.