Specifications include, but are not limited to: Southern California Association of Governments (SCAG) serves as the metropolitan planning organization (MPO) for Imperial, Los Angeles, Orange, Riverside, San Bernardino, and Ventura counties. The SCAG region encompasses a population of more than 19 million people in an area exceeding 38,000 square miles. As the MPO for the region, SCAG is responsible for the development and maintenance of travel demand and air quality models for the Southern California areas. The models provide state of the practice quantitative analysis for the Regional Transportation Plan and Sustainable Communities Strategy (RTP/SCS), the Federal Transportation Improvement Program (FTIP), and Air Quality Management Plan (AQMP).