Under federal law, states must establish a metropolitan planning organization (MPO) for each urban area with a population of at least 50,000. MPOs are subject to a variety of requirements, including the obligation to engage in a continuing, comprehensive, and cooperative transportation planning process for the urban area for which it has been established. Under current law, MPOs may consider a project’s potential for reducing greenhouse gas emissions, but it is not required. The model federal legislation accompanying this memorandum would establish such a requirement. Under the bill, the metropolitan planning process would be required to provide for consideration of projects and strategies that will reduce the amount of greenhouse gases produced by the transportation system.