A TMA is designated by the U.S. Secretary of Transportation for an urbanized area with a population of at least 200,000. Congress provided for this greater role by MPOs through a certification review aimed at formalizing the continuing oversight and day-to-day evaluation of the planning process. MPOs attaining certification enjoy certain benefits, but they also incur additional requirements beyond those of smaller urbanized areas for congestion management, project selection, and certification. For more information about the certification process, please see chapter 11 of this manual. The FHWA and FTA jointly review and evaluate the transportation planning process every four years. In air quality nonattainment or maintenance areas, the FHWA and FTA review to ensure that TMAs follow air quality conformity regulations.