The following types of foreign-born people qualify as immediate relatives:
Spouses of U.S. citizens. This includes couples who are legally married (regardless of where the marriage took place), as well widows and widowers of U.S. citizens if they were married to the U.S. citizen for at least two years and are applying for a green card within two years of the U.S. citizen’s death.
Unmarried children of a U.S. citizen, under the age of 21, (see the definition of “child” for U.S. immigration law purposes), and
Parents of U.S. citizens, if the U.S. citizen child is age 21 or older. (Parents of permanent residents have no immigration option through their children unless and until those children become U.S. citizens)
Stepparents and stepchildren qualify as immediate relatives if the marriage creating the parent/child relationship took place before the child’s 18th birthday. Parents and children related through adoption may also, in some cases, qualify as immediate relatives.