This chapter explains the transportation planning that practiced at the municipal and metropolitan levels. By 2009 the US population had grown to 304 million, a factor of about 2.3. Automobile registrations had grown to 135 million, a factor of 5.5. But that figure greatly understates the growth of privately owned automotive transportation, Widespread automobile ownership facilitates suburbanization. On the other hand, moving from the central city to the suburbs increases one's need for an automobile. One powerful force behind the increase in automobile ownership was the large increase in average real personal income in the years following World War II. Public transportation usage peaked in the last year of World War II. Public transportation usage is distributed very unevenly in the United States. To understand transportation policy, it is important to understand how private and public transportation are financed. Transportation planning is a basic function of many planning agencies, for adequate circulation traditionally has been a major planning goal.