Transportation consumes about 25 percent of the nation's energy budget; about 96 percent comes from petroleum. This use is growing about 4 percent annually, due to changes in average modal energy intensiveness, increasing population, and growing per capita use of transportation. Emerging petroleum supply problems will cause prices to increase. These problems result from the increasing difficulty of supplying fuels in an environmentally acceptable way and the facts that increasing amounts of imported oil will be required to meet projected demands, and oil supplies are ultimately limited. As the growing demand for transportation energy comes into conflict with rising energy prices, transportation systems will undergo changes in the direction of less energy intensive transportation modes for people and freight, and less transportation per capita. New perceptions of the role of transportation in society may result, helping to bring about urban developments minimizing transportation, innovative communication methods which substitute for travel, and changed ideas about vacations. 25 pp. Ref.