In immigration matters, children of naturalized U.S. citizens are granted special priority. The law makes a distinction, though, based on the marital status and age of the child involved. That is, unmarried children under 21 years of age are categorized as immediate relatives, while married children and children over 21 are placed in the family preference category. Immediate relatives living in Florida or elsewhere have a simpler path to permanent residency because an unlimited number of visas have been made available for people who meet the requirements of the category. Immediate relatives of U.S. citizens need not wait for a visa number and may begin the process of securing permanent residency by filing Form I-485 at the same time that the citizen sponsor files Form I-130. Other forms may be required as well.
Those in the family preference category, on the other hand, must usually wait for a visa to come available. For a family member who is in the U.S., the citizen sponsor should file Form I-130 first, and then the parties must wait for approval and for the relevant priority date to come current. When that happens, the family member may file Form I-485.
A family member who is outside the U.S. must proceed through consular processing. Once the sponsor's Form I-130 is approved, the Department of State will issue a visa for the family member to enter the U.S., and the family member will be granted permanent residency at the U.S. port of entry.
Each individual immigration situation is unique and decisions of U.S. Citizenship and Immigration Services may vary based on the facts of the case. Those who have questions about family immigration may want to discuss the matter with an immigration and naturalization lawyer who may be able to help a client navigate the process and draft and file the correct forms.Source: Green Card Through Family, "Green Card for a Family Member of a U.S. Citizen," U.S. Citizenship and Immigration Services, Oct. 28, 2014
Source: USCIS, "U.S. Citizenship", October 28, 2014