Change is coming fast in the Third World. Unprecedented population growth and its concentration in one or a few giant urban centers in each country are the most evident signs of this change. For example, the Third World's population is currently growing at a rate of about 1.9 percent per year (Population Reference Bureau 1996). Since 1950, the population of the Third World has grown by 173 percent, from 1,681 million (Merrick 1986: 12-13) to an estimated 4,600 million in 1996 (Population Reference Bureau 1996). During the same period world population rose by 129 percent, from 2,516 million to 5,771 million. Because of its faster rate of growth, the Third World's share of global population rose from 67 percent in 1950 to 81 percent in 1996.