In 1973, the Federal Transportation Act required that each urbanized area (area with 50, 000 or more population) establish a Metropolitan Planning Organization (MPO). The federal law required that the Governor of the state designate the agency to serve as the MPO. MAG was designated as the MPO for this region in 1973.
In 1991, President Bush signed into law the Intermodal Surface Transportation Efficiency Act (ISTEA). This Act enunciated its statement of policy as follows: "To develop a National Intermodal Transportation System that is economically efficient, environmentally sound, provides the foundation for the Nation to compete in the global economy and will move people and goods in an energy efficient manner."
ISTEA recognized the challenge of addressing congestion and air quality issues in urbanized areas and determined that MPOs could address these issues. The enhanced planning role for MPOs was defined in the ISTEA regulations as follows: "Metropolitan Planning Organizations, in cooperation with the State, shall develop transportation plans and programs for urbanized areas of the State. Such plans and programs shall provide for the development of transportation facilities which will function as an intermodal transportation system for the State, the metropolitan areas, and the Nation. The process for developing such plans and programs shall provide for consideration of all modes of transportation and shall be continuing, cooperative, and comprehensive to the degree appropriate, based on the complexity of the transportation problems."
ISTEA requires MPOs to have a proactive public involvement process and to represent all modes of transportation. In addition to receiving greater requirements, MPOs were also provided a larger amount of federal transportation funding.
In Maricopa County, the Maricopa Association of Governments serves as the MPO for the Maricopa County area. The Pima Association of Governments serves as the designated MPO for the Pima County region. In Yuma County, the Yuma Metropolitan Planning Organization serves as the MPO for the Yuma urbanized area. The Flagstaff Metropolitan Planning Organization serves as the MPO for the Flagstaff urbanized area and Central Yavapai Metropolitan Planning Organization serves as the MPO for the Central Yavapai region. The Lake Havasu Metropolitan Planning Organization serves as the MPO for the Lake Havasu City urbanized area. In Pinal County, the Sun Corridor Metropolitan Planning Organization serves as the MPO for the Pinal County region. In Cochise County, the Sierra Vista Metropolitan Planning Organization serves as the MPO for the Sierra Vista urbanized area.