The CMAQ Program was created by the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) to assist cities in attaining federal air quality guidelines. Funds are distributed to states based on weighted non-attainment and maintenance area population. Legislation authorizes the expenditure of CMAQ funds on projects with a documented emissions reduction associated with them and are available for use only in non-attainment and maintenance areas, or as determined by federal law for ozone and particulate matter pollution. In Missouri, the CMAQ Program is limited to the Kansas City and St. Louis metropolitan areas. Typical activities include revisions and installation of traffic signals, signal timing optimizations, developing transportation management systems, public transportation facilities, and activities to encourage car pooling and van pooling.