The Los Angeles Basin (Basin) or the Los Angeles five-county area (Los Angeles, Orange, Riverside, San Bernardino, and Ventura) sprawls over more than 35,000 square miles and encompasses 178 incorporated cities (33 of which have a population of more than 100,000). The population of the Basin, exceed ing over 16 million in 1999, is the most cosmopolitan in the world. If the Basin were a separate state, it would rank fourth in the nation. By the year 2020, the Basin population is expected to reach 21.5 million. Based on the gross product for 1996, the Los Angeles Basin's economy ranks 12th in the world. 

Three major factors are driving population growth-natural increase, internal migration, and immigration. Internal migration is the most volatile among these factors, since it is general ly responsive to the number of available jobs. Over the past two decades, the Los Angeles Basin experienced its first net out-migration during the 1991-93 recession. However, with the recent economic growth and number of jobs, the number of people leaving the Basin has leveled off as compared to the early 1990s. At the same time, there has been an increase in the number of people moving in from other parts of the nation. 

The Basin is also undergoing a major shift in its ethnic composition. According to the 1990 Census, 52 percent of the Los Angeles Basin's population was White, 31 percent Hispanic, 8 percent Black, and 9 percent Asian. By the year 2020, it is forecasted that the proportion of the Whites and Blacks will decline to 31 percent and 6 percent respectively. In the same period, the proportion of Hispanics will increase to 49 percent and that of the Asians will increase to 13 percent.