Preference Categories
The relative you wish to immigrate must obtain an immigrant visa number that is based on the preference category in which they fall.
People who want to become immigrants are classified into categories based on a preference system. The immediate relatives of U.S. citizens, which includes parents, spouses and unmarried children under the age of 21, do not have to wait for an immigrant visa number to become available once the visa petition filed for them is approved by the USCIS. An immigrant visa number will be immediately available for immediate relatives of U.S. citizens. The relatives in the remaining categories must wait for an immigrant visa number to become available according to the following preferences:
First Preference: Unmarried, adult sons and daughters of U.S. citizens. Adult means 21 years of age or older.
Second Preference: Spouses of lawful permanent residents, their unmarried children (under twenty-one), and the unmarried sons and daughters of lawful permanent residents.
Third Preference: Married sons and daughters of U.S. citizens.
Fourth Preference: Brothers and sisters of adult U.S. citizens.
Once USCIS receives your visa petition, I-130, Petition for Alien Relative, it will be approved or denied. USCIS will notify the person who filed the visa petition if the visa petition is approved. USCIS will then send the approved visa petition to the Department of State’s National Visa Center, where it will remain until an immigrant visa number is available. The Center will notify you, the foreign national, when the visa petition is received and again when an immigrant visa number is available. You do not need to contact the National Visa Center, unless you change your address or there is a change in your personal situation, or that of your alien relative, that may affect eligibility for an immigrant visa, such as reaching age 21, marriage, divorce, or death of a spouse.
Source: The U.S. Citizenship and Immigration Services (USCIS)
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