Era of Restriction
Mass immigration resumed after the First World War. Congress responded with a new immigration policy, the national origins quota system. Established by Immigration Acts of 1921 and 1924, the national origins system numerically limited immigration for the first time in United States history. Each nationality received a quota based on its representation in past United States census figures. The State Department distributed a limited number of visas each year through U.S. Embassies abroad and the Immigration Service only admitted immigrants who arrived with a valid visa.
Birth of the Border Patrol and Board of Review
Severely restricted immigration often results increased illegal immigration. In response to rising numbers of illegal entries and alien smuggling, especially along land borders, in 1924 Congress created the U.S. Border Patrol within the Immigration Service.
The strict new immigration policy coupled with Border Patrol successes shifted more agency staff and resources to deportation activity. Rigorous enforcement of immigration law at ports of entry also increased appeals under the law. This led to creation of the Immigration Board of Review within the Immigration Bureau in the mid-1920s. (The Board of Review became the Board of Immigration Appeals after moving to the Justice Department in the 1940s, and since 1983 has been known as the Executive Office of Immigration Review (EOIR).)
United Immigration and Naturalization Service (INS)
Executive Order 6166 of June 10, 1933, reunited the Bureau of Immigration and Bureau of Naturalization into one agency, the Immigration and Naturalization Service. Consolidation resulted in significant reduction of the agency's workforce achieved through merit testing and application of Civil Service examination procedures.
The agency’s focus shifted towards law enforcement as immigration volume dropped significantly during the Great Depression. Through the 1930s, INS dedicated more resources to investigation, exclusion, prevention of illegal entries, deportation of criminal and subversive aliens, and cooperating closely with the Department of Justice's United States Attorneys and Federal Bureau of Investigation (FBI) in prosecuting violations of immigration and nationality laws.