Non-immediate relatives of citizens, as well as relatives of immigrants who already have green cards, receive a priority ranking that determines whether and when they receive green cards. The highest priority is given to unmarried adult children of citizens, followed by spouses and unmarried children of those with green cards, married children of citizens, then brothers and sisters of citizens. Because of a glut of applications, Mexican nationals in these categories have been waiting from six to 11 years for permission to enter the country. These cards are subject to quotas. Most people in this category must have permanent-job offers, but employers don't have to prove that no U.S. workers are available.
Third preference is for skilled workers and professionals with bachelor's degrees.
In these two categories, most immigrants must be sponsored by their employers, who must go through labor certification.