"About 5.0 million undocumented immigrants were residing in the United States in October 1996, with a range of about 4.6 to 5.4 million (See Table 1). The population was estimated to be growing by about 275,000 each year, which is about 25,000 lower than the annual level of growth estimated by the INS in 1994. California is the leading state of residence, with 2.0 million, or 40 percent of the undocumented population. The 7 states with the largest estimated numbers of undocumented immigrants-- California (2.0 million), Texas (700,000), New York (540,000), Florida (350,000), Illinois (290,000), New Jersey (135,000), and Arizona (115,000)--accounted for 83 percent of the total population in October 1996. The 5.0 million undocumented immigrants made up about 1.9 percent of the total U.S. population, with the highest percentages in California, the District of Columbia, and Texas. In the majority of states, undocumented residents comprise less than 1 percent of the population."
Department of Homeland Security: http://www.dhs.gov/index.shtm