Immigrant Visas
Family Based Visas
The Immigration and Nationality Act allows for the immigration of foreigners to the United States based on relationship to a U.S. citizen or legal permanent resident. Family-based immigration falls under two basic categories: unlimited and limited.
UNLIMITED FAMILY-BASED
Immediate Relatives of U.S. Citizens (IR): 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 Residents (SB): Immigrants who lived in the United States previously as lawful permanent residents and are returning to live in the U.S. after a temporary visit of more than one year abroad.
LIMITED FAMILY-BASED
Family First Preference (F1): Unmarried sons and daughters of U.S. citizens, and their children, if any (23,400).
Family Second Preference (F2): Spouses, minor children, and unmarried sons and daughters (over age 20) of lawful permanent residents (114,200). At least seventy-seven percent of all visas available for this category will go to the spouses and children; the remainder will be allocated to unmarried sons and daughters.
Family Third Preference (F3): Married sons and daughters of U.S. citizens, and their spouses and children (23,400).
Family Fourth Preference (F4): Brothers and sisters of United States citizens, and their spouses and children, provided the U.S. citizens are at least 21 years of age (65,000).
More information at: http://travel.state.gov/visa/immigrants/types/types_1306.html