Immediate Relatives and Family Preference Categories

Immediate Relatives

One of the easiest ways to immigrate is to have an immediate relative who is a U.S. citizen. Spouses and minor (i.e., under 21) unmarried children of United States citizens, parents of United States citizens (provided the citizen is over 21 years old), and certain spouses of deceased United States citizens can qualify for immigrant visas as immediate relatives. There are no numerical limitations on this category.

In addition,

aliens who are born after the issuance to an alien of an immediate relative visa, but before it is used to apply for admission to the United States; and
aliens born to a lawful permanent resident during a "temporary visit" abroad, are likewise not generally subject to numerical limitations, and have similar immigration benefits as the individuals described in the paragraph above.

Family Sponsored Preference Immigrants

If you don't have an immediate relative who is a U.S. citizen, then you may still qualify for family-based immigration, if you are:

the adult unmarried son or daughter of a U.S. citizen,
the spouse or minor child of a permanent resident, OR the adult unmarried son or daughter of a permanent resident,
the married son or daughter of a U.S. citizen, OR
the adult brother or sister of a U.S. citizen.;

Each of these categories has different characteristics, the most important of which has to do with the maximum number of visas that may be granted each year (which, consequently, affects the waiting period involved):

The current family-based preference categories and annual numerical limits are:

Family First Preference (unmarried sons and daughters of U.S. citizens): 23,400 visas
Family Second Preference ((a.) spouses and unmarried minor children of permanent resident aliens and (b) unmarried adult sons and daughters of permanent resident aliens): 114,200 visas
Family Third Preference (married sons and daughters of U.S. citizens): 23,400 visas
Family Fourth Preference (adult brothers and sisters of U.S. citizens): 65,000 visas

The waiting period or backlog for each category is indicated on the Visa Bulletin published monthly by the State Department.