Illegal immigration to the United States

Foreign nationals (aliens) can violate US immigration laws by entering the United States unlawfully or lawfully entering but then remaining after the expiration of their visas, parole, or temporary protected status. Illegal immigration has been a matter of intense debate in the United States since the 1980s.

The illegal immigrant population of the United States peaked by 2007, when it was at 12.2 million and 4% of the total U.S. population. Estimates in 2016 put the number of illegal immigrants at 10.7 million, representing 3.3% of the total U.S. population. Since the Great Recession, more illegal immigrants have left the United States than entered it, and illegal border crossings were at the lowest in decades until 2021, when a record of 1.7 million people were caught trying to cross the southern border illegally. Since 2007, visa overstays have accounted for a larger share of the growth in the illegal immigrant population than illegal border crossings, which have declined considerably from 2000 to 2018. In 2012, 52% of illegal immigrants were from Mexico, 15% from Central America, 12% from Asia, 6% from South America, 5% from the Caribbean, and another 5% from Europe and Canada. As of 2016, approximately two-thirds of illegal adult immigrants had lived in the U.S. for at least a decade.

Opponents of illegal immigration argue that people who enter the United States illegally are criminals, as well as social and economic burdens on law-abiding natives. Opponents also argue that illegal immigrants who enter the United States illegally should be deported instead of being awarded with U.S. citizenship and social services. Some argue that illegal immigrants should instead enter the United States lawfully through legal immigration.

Research shows that illegal immigrants increase the size of the U.S. economy, contribute to economic growth, enhance the welfare of natives, contribute more in tax revenue than they collect, reduce American firms' incentives to offshore jobs and import foreign-produced goods, and benefit consumers by reducing the prices of goods and services. Economists estimate that legalization of the illegal immigrant population would increase the immigrants' earnings and consumption considerably, and increase U.S. gross domestic product. There is scholarly consensus that illegal immigrants commit less crime than natives. Sanctuary cities—which adopt policies designed to avoid prosecuting people solely for being in the country illegally—have no statistically meaningful impact on crime. Research suggests that immigration enforcement has no impact on crime rates.