Family Based Immigration The Immigration and Nationality Act allows for the immigration of family members to the United States. Immediate Relatives of U.S. Citizens: The spouse, widow(er) and unmarried children under 21 of a U.S. citizen, and the parent of a U.S. citizen who is 21 or older. Returning Legal Permanent Residents: Immigrants who lived in the United States previously as legal permanent residents and are returning to live in the U.S. after a temporary visit of more than one year abroad. First Preference: Unmarried sons and daughters of U.S. citizens, and their children. Second Preference: Spouses, minor children, and unmarried sons and daughters (over age 21) of lawful permanent residents. Third Preference: Married sons and daughters of U.S. citizens, and their spouses and children. Fourth Preference: Brothers and sisters of United States citizens, and their spouses and children, provided the U.S. citizens are at least 21 years of age.