The Department of Homeland Security (DHS) has published the estimate report of the unauthorized immigrant population residing in the US in January 2005 by period of entry, country of origin, and state of residence. Following is the summary of the estimate report:

There were an estimated 10.5 million unauthorized immigrants residing in the United States in January 2005 compared to 8.5 million in January 2000. During the 2000-2004 period, the unauthorized resident population grew at an annual average rate of 408,000. Assuming this same rate of growth, the unauthorized immigrant population would have reached nearly 11 million by January 2006.

Almost 3.1 million of the 10.5 million unauthorized residents in 2005 had come to live in the United States in 2000 or later. An estimated 1.0 million entered the United States in 2003 or 2004, while 2.1 million arrived during 2000 through 2002.

Mexico was the leading source country for unauthorized immigration with nearly 6.0 million residents in the United States in 2005. El Salvador, Guatemala, India, and
China were the next leading source countries, accounting for a combined total of nearly 1.4 million unauthorized immigrants. Among the 10 leading source countries, the annual average increase in the unauthorized population from 2000 to 2005 was greatest among Mexican immigrants (260,000). However, the greatest percentage increase in the unauthorized immigrant population from 2000 to 2005 occurred among immigrants from India (133 percent) and Brazil (70 percent).

California was home to more unauthorized residents than any other state. In January 2005, an estimated 2.8 million unauthorized immigrants lived in California, followed by Texas with nearly 1.4 million and Florida with 850,000. Among the 10 leading states of residence of the unauthorized population in 2005, those with the largest average annual increases since 2000 were Texas (54,000), California (52,000), and Georgia (50,000). The states with the greatest percentage increases in unauthorized immigrants from 2000 to 2005 were Georgia (114 percent), Arizona (45 percent), Nevada (41 percent), and North Carolina (38 percent).

These estimates were calculated using a “residual method,” whereby estimates of the legally resident foreign-born population as of January 1, 2005 were subtracted from the total foreign-born population at the same point in time. Estimates of the legally resident foreign-born were based primarily on administrative data of the Department of Homeland
Security (DHS), while estimates of the total foreign-born population were obtained from the American Community Survey (ACS) of the U.S. Census Bureau. The starting point for the estimates was 1980, as persons who entered the United States earlier were assumed to be legally resident.