Accelerated urbanization in the Third World has spurred the concentration of political powers within cities, leading to policies that favor urban over rural areas. Population growth in Third World cities is outpacing city and national budgets and straining urban institutions. Urbanization has three demographic components: migration, natural increase, and reclassification of rapidly developing rural areas to cities. Land and water scarcity, inefficient energy use and waste disposal, and the resultant problems of pollution all contribute to the escalating ecological and economic costs of supporting modern cities. Both the ecology and economics of renewable energy sources suggest that the future will favor smaller cities and those who live in rural areas. Nutrient recycling is likely to increase in popularity as urban land, water, and energy resources become scarcer and as waste management strategies improve. The evolution of urban settlements placed in the context of human history, has long been considered a benchmark of economic success.