Immigration in America reports that the National Origins Act was another name for the Immigration Act of 1924, which was also known as the Asian Exclusion Act. The act was a piece of federal legislation that determined immigration quotas per country based on the number of people from that country already living in the United States. Immigration in America calls the National Origins Act the first large-scale attempt to restrict immigration.
The National Origins Act relied on census data from 1890, according to the U.S. Department of State Office of the Historian. The legislation provided immigration visas for 2 percent of a country's population based on the number of people who claimed that nationality in the 1890 census. Previous immigration laws based quota numbers off of the 1910 census data. The Office of the Historian explains that the National Origins Act intentionally switched to an earlier version of the census data to have a legal basis for reducing the number of immigration visas.
No immigrants from Asia were permitted under the National Origins Act, according to the Office of the Historian. Under previous immigration laws, such as the Gentlemen's Agreement, Japanese immigrants had been allowed. The Japanese government protested, but the U.S. government refused to change the legislation. According to the Office of the Historian, this led to a strained relationship between the two countries.