Certain airport environs are identified and established by these airport overlay regulations for property within and around Scott Air Force Base (AFB) and MidAmerica St. Louis Airport (MidAmerica) within St. Clair County, Illinois. These environs have been identified through Federal Aviation Regulations Part 77 and data provided to St. Clair County by the United States Air Force as part of the 2008 Joint Land Use Study and the 2009 Air Installation Compatible Use Zone (AICUZ) report. Areas within the airport environs are subject to regulation beyond the other requirements of the Development Code. These additional restrictions, designated as the Airport Overlay (AO) District, provide an enhanced level of protection in support of the continued operations of Scott AFB and MidAmerica St. Louis Airport.