"This report presents estimates of the legal permanent resident (LPR) population living in the United States on January 1, 2006. The LPR population includes persons granted lawful permanent residence, e.g. 'green card' recipients, but not those who had become U.S. citizens. The estimates are shown for the total LPR population and the LPR population eligible to apply to naturalize by country of birth, state of residence, and the year LPR status was obtained. Data for the estimates were obtained primarily from administrative records of U.S. Citizenship and Immigration Services (USCIS) of the Department of Homeland Security (DHS). The methodology used for the 2006 estimates is similar to that used in previous DHS estimates (see Rytina, 2004, 2005, and 2006). Minor changes in assumptions, made to be consistent with DHS estimates of the unauthorized population, had little effect on the estimates. In summary, an estimated 12.1 million LPRs lived in the United States on January 1, 2006. The LPR population remained relatively stable between 2004 and 2006-increasing by 5 percent. Data on the size and characteristics of the foreign-born population are needed to assess the impact of immigration and integration of immigrants into U.S. society. The decennial census and monthly household surveys of the Census Bureau include questions on place of birth, citizenship, and year of entry into the United States. These data provide a wealth of information on the total foreign-born population, naturalized citizens, and non-citizens."
United States Department of Homeland Security: http://www.dhs.gov/