The process of urbanization, known to be intimately associated with economic development, deserves close attention if we are to understand the recent and future mechanisms of change in pre-industrial areas. Considerable interest was shown in the subject toward the end of the last century-in the works of Levasseur, Meuriot, and Adna Weber-but since then, except for isolated cases such as Pirenne and Mark Jefferson, there has been little work done in the comparative analysis of cities and urbanization. With respect to urbanization, there can be no doubt that the underdeveloped areas of the world have less of it than the advanced areas. If authors take as underdeveloped, or pre-industrial, all areas with more than 50 percent of their occupied males engaged in agriculture, they find that only 9 percent of their combined population lives in cities of 100,000 or over, whereas for the other countries (industrial) the proportion is 27 percent.