The rapid growth and expansion of cities in developing countries in the last one-and-a-half decades are forcing a study of various aspects of urbanization on intellectuals. Some of the fields that draw the interest of researchers are patterns of migration, diffusion process, and urban hierarchy. Prospective migrants are not equally attracted to all cities; they have preferences depending on their chief aims. Some cities attract more people than do others. Partly for that reason, we have a hierarchy of cities. The mere population size of a city may, in itself, be unimportant, but the responsibilities that a heavily populous city forces on its administration are usually significant. The availability of goods and services, the range of these goods and services as well as the price paid for the distance in money and comfort, are all very important.