U.S. citizens can also sponsor their unmarried children that are under 21, married children that are any age, and siblings. Additionally, lawful permanent residents can sponsor their spouse, children under 21, and unmarried sons or daughters are over 21. The immigrant visas for these relatives will not be readily available. in fact, after applying to put the beneficiary in line, these types of relatives will usually have to wait a certain number of years before a visa is available.