What is the fine-grained topic of the following text: The national-origins quota system passed of 1921, Bracero programme 1942, McCarran–Walter Act of 1952, The immigration act of 1973, Immigration Reform and Control Act (IRCA ) of 1986, 1990 Immigration Act, Illegal Immigrant Reform and Immigrant Responsibility Act (IIRIRA) of1996, the Border Protection, Anti-terrorism, and Illegal Immigration Control Act of 2005, Comprehensive Immigration Reform Act of 2006 (CIRA), and the Comprehensive Immigration Reform Act of 2007. Only return the topic.
U.S. Immigration Laws and Reforms