It limited the number of immigrants that could be admitted to the U.S. to two percent of the total number of individuals from each nationality that resided in the United States in 1890—before waves of Slavic and Italian immigrants arrived in America. Despite vigorous protests from Japanese diplomats, the measure also excluded Japanese immigrants (a ban that would not be lifted until 1952). Finally, it allowed no more than 150,000 total immigrants who fell within the parameters of the quota system to enter the U.S. in any one year. After Senate passage, the Immigration Act was signed into law in late May 1924. History.house.gov
This law set restrictive quotas on the numbers of immigrants that were allowed to enter the country and it based this number on results from the 1890 census. However, it only set quotas for countries outside of the Americas. How was immigration from a country like Colombia controlled? With the exception of Mexico, which shares a border with the US, there are no old Latino immigrant communities. Immigrant communities from South America are fairly recent. Why is that?