Immigration is the international movement of people to a destination country of which they are not natives or where they do not possess citizenship in order to settle as permanent residents or naturalized citizens. Commuters, tourists, and other short-term stays in a destination country do not fall under the definition of immigration or migration; seasonal labour immigration is sometimes included, however.

Immigration has been a major source of population growth and cultural change throughout much of the history of the United States. In absolute numbers, the United States has a larger immigrant population than any other country in the world, with 47 million immigrants as of 2015. This represents 19.1% of the 244 million international migrants worldwide, and 14.4% of the United States' population.

The Chinese Exclusion Act was a United States federal law signed by President Chester A. Arthur on May 6, 1882, prohibiting all immigration of Chinese laborers for 10 years. The law excluded merchants, teachers, students, travelers, and diplomats. The Chinese Exclusion Act was the first and only major U.S. law ever implemented to prevent all members of a specific national group from immigrating to the United States.

The Immigration Act of 1924, or Johnson–Reed Act, including the Asian Exclusion Act and National Origins Act, was a United States 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 Page Act of 1875 was the first restrictive federal immigration law in the United States, which effectively prohibited the entry of Chinese women, marking the end of open borders. Seven years later, the 1882 Chinese Exclusion Act banned immigration by Chinese men as well.

The United States Immigration Commission was a bipartisan special committee formed in February 1907 by the United States Congress, President of the United States and Speaker of the House of Representatives, to study the origins and consequences of recent immigration to the United States. This was in response to increasing political concerns about the effects of immigration in the United States and its brief was to report on the social, economic and moral state of the nation. During its time in action the Commission employed a staff of more than 300 people for over 3 years, spent better than a million dollars and accumulated mass data.