Last week, the Supreme Court invalidated much of Arizona's controversial immigration law, ruling that aspects of the state's law cracking down on illegal immigration were preempted by federal authority.
Nationwide, just under 40 million U.S. residents — 13 percent — were classified by the Census as "foreign-born" in 2010. That category includes 17.5 million naturalized citizens and 22.5 million non-citizens, and it excludes those born abroad to American parents.
The Census does not provide statistics on illegal immigration, but the Pew Hispanic Center has estimated the population of unauthorized immigrants in the United States at 11.2 million in 2010.
The map shows the foreign-born share of the population by Congressional district in 2000, 2005 and 2010. Clicking on a district provides more detailed information along with statistics for the state at large.
About the Data
The figures in the map were estimated by the Census Bureau based on responses to the American Community Survey, a set of social and economic questions asked annually of a representative group of American households. (For 2000, comparable data was collected in the Decennial Census long form).
Because the figures are based on samples, they are estimates, not absolute counts. Census data is made available through the American FactFinder portal.
The Pew Hispanic Center’s report on the population of unauthorized immigrants can be found here.