This paper attempts to summarize many of these empirical regularities about metropolitan development and its determinants. Although much of our knowledge about metropolitan development is still imperfect, in the past 35 years a great deal of theoretical and empirical work has been carried out on...

Motorization grows in proportion to income at the national and urban level, as do paved roads at the national level; urban roads grow much more slowly than income. Using panel data from 50 countries and 35 urban areas (covering a wide range of country incomes), Ingram and Liu summarize trends in...