Provided is an overview of the Nation's transportation system which identifies future investments required to maintain and develop its infrastructure. The contents of this study were used in support of the National Transportation Policy Statement, issued by the Department of Transportation during March 1990. It is organized around a framework in which transportation is viewed as an integral part of our socioeconomic system. The future development of transportation will be influenced by the same factors affecting the rest of the system, namely, demographic changes, the future course of the economy, the energy supply, and preservation of the environment.