The Immigration Act of 1924, or Johnson–Reed Act, including the Asian Exclusion Act and National Origins Act, was a federal law that prevented immigration from Asia and set quotas on the number of immigrants from Eastern and Southern Europe. It also authorized the creation of the country's first formal border control service, the U.S. Border Patrol, and established a "consular control system" that allowed entry only to those who first obtained a visa from a U.S. consulate abroad.

The United States Border Patrol (USBP) is a federal law enforcement agency under the United States Customs and Border Protection (CBP) and is responsible for securing the borders of the United States. According to its web site in 2022, its mission is to "Protect the American people, safeguard our borders, and enhance the nation’s economic prosperity."