Illegal immigration to the United States

Illegal immigration, or unauthorized immigration, occurs when foreign nationals, known as aliens or non-citizens, violate US immigration laws by entering the United States unlawfully, or by lawfully entering but then remaining after the expiration of their visas, parole or temporary protected status. Between 2007 and 2018, visa overstays accounted for a larger share of the growth in the undocumented immigrant population of the United States than illegal border crossings, which have declined considerably from 2000 to 2018. In 2022, 37% of unauthorized immigrants were from Mexico, the smallest share on record. El Salvador, India, Guatemala and Honduras were the next four largest countries. As of 2016, approximately two-thirds of unauthorized adult immigrants had lived in the US for at least a decade. As of 2022, unauthorized immigrants made up 3 % of the US population, though nearly one-third of those immigrants have temporary permission to be in the United States, such as those in Deferred Action for Childhood Arrivals. According to an August 2025 Pew Research Center report, the unauthorized immigrant population grew by 3 million between 2021 and 2023, reaching a record 14 million. July 2024 data for border crossings showed the lowest level of border crossing since September 2020. Opponents of illegal immigration worry about crime, as well as possible social and economic burdens caused by migration. However, studies and FBI data have consistently found that undocumented immigrants are less likely to commit crimes than native-born citizens in the United States. In Texas, for example, undocumented immigrants are arrested for violent and drug crimes at less than half the rate of native-born U . citizens, and a quarter the rate of native-born citizens for property crimes. Opponents also insist immigrants enter the United States through a formal process and do not want to reward those bypassing the system. Research shows that illegal immigration increases the size of the US economy, contributes to economic growth, enhances the welfare of natives, contributes more in tax revenue than they collect, reduces American firms' incentives to offshore jobs and import foreign-produced goods, and benefits 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 US gross domestic product. Most scientific studies have shown that undocumented immigrants commit less crime than natives and legal immigrants. 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.