There are 115 Fast Food Restaurants in St. Clair County, Illinois, serving a population of 264,433 people in an area of 658 square miles. There is 1 Fast Food Restaurant per 2,299 people, and 1 Fast Food Restaurant per 5 square miles.
In Illinois, St. Clair County is ranked 28th of 102 counties in Fast Food Restaurants per capita, and 6th of 102 counties in Fast Food Restaurants per square mile.