The U.S. Immigration System is governed by the Immigration and Nationality Act. The INA allows the United States to grant up to 675,000 permanent immigrant visas each year across various visa categories. There is no limit placed on the annual admission of U.S. citizens’ spouses, parents, and children under the age of 21. Additionally, the President consults with Congress to set an annual number of refugees admitted. Asylum and Temporary Protection Status is also granted.
Timeline: U.S. Immigration Policy
In-depth timeline covering U.S. immigration tailored to specific topics
Library of Congress immigration information and timeline