[2] The primary responsibility of Chicago Center is sequencing and separation of over-flights, arrivals, and departures in order to provide safe, orderly, and expeditious flow of aircraft.
Chicago Center covers approximately 91,000 square miles (240,000 km2) of the Midwestern United States, including parts of Illinois, Indiana, Michigan, Wisconsin, and Iowa.
ZAU overlies or abuts many approach control facilities (including Chicago, Milwaukee, Madison, Cedar Rapids, Des Moines, the Quad Cities, Peoria, Springfield, Indianapolis, and Grand Rapids approaches).
Chicago Center is the tenth busiest ARTCC in the United States.
[3] On September 26, 2014, an arson at the Chicago Center (ZAU) facility caused operations across ZAU-controlled airspace to be suspended, including airport operations at Chicago's O'Hare and Midway International Airports, resulting in canceled flights.