Fayette County is a county located in the U.S. state of Illinois. As of the most recent data available, the county has a population of approximately 21,802 people, with a population density of about 30.41 persons per square mile.
The county spans a total land area of 717.00 square miles (1,857.00 square kilometers). The administrative center and county seat is Vandalia, which often serves as a hub for local governance and services. The largest city within the county by population is Vandalia.
Geographically, Fayette County experiences varied elevations, with its highest point at St. Elmo 619 ft and its lowest point at Vandalia 515 ft. The region operates in the UTC-6.