Many acts of Congress and executive actions relating to immigration to the United States and citizenship of the United States have been enacted in the United States. Most immigration and nationality laws are codified in Title 8 of the United States Code.
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 have 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 unauthorised adult immigrants had lived in the US for at least a decade. As of 2022, unauthorized immigrants made up 3.3% 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 3.5 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.
Illegal immigration, or unauthorized immigration, occurs when foreign nationals, known as aliens, 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 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 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 unauthorised adult immigrants had lived in the US for at least a decade. As of 2022, unauthorized immigrants made up 3.3% 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 3.5 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.
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 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 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 unauthorised adult immigrants had lived in the US for at least a decade. As of 2022, unauthorized immigrants made up 3.3% 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 3.5 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.