If your relationship does not qualify as an immediate relative of a U.S. citizen, then the foreign national may be in what is called a “family preference category.”
U.S. citizens can petition for unmarried sons or daughters over the age of 21, for married children of any age, and for siblings. Please note that the U.S. citizen petitioner must be 21 or older.
A permanent resident may petition for his or her spouse and unmarried children of any age to immigrate to the United States. Permanent Residents cannot petition for any other relative (that includes married children, siblings, fiancé(e)s or parents).
The family preference categories dictate how quickly a visa number may be available. Depending on the type of relationship and the country of birth of the beneficiary, the wait could be over ten years. To view the priority dates for the family preference categories, please review the Visa Bulletin, which is published by the U.S. Department of State.