The Interstate Highways in Illinois are all segments of the Interstate Highway System that are owned and maintained by the U.S. state of Illinois. The Illinois Department of Transportation (IDOT), Illinois State Toll Highway Authority (ISTHA), and Skyway Concession Company (SCC) are responsible for maintaining these highways in Illinois. The Interstate Highway System in Illinois consists of 13 primary highways and 11 auxiliary highways which cover . The Interstate Highway with the longest section in Illinois is Interstate 57 at ; the shortest is Interstate 41 at .