“Immediate relatives” of a U.S. citizen, such as parents, spouses, widows, and unmarried children under the age of 21 can immigrate to the United States without any restrictions. They can apply for permanent resident status without any waiting time. Other relatives are divided into several preference categories. Each preference is given a numerical quote per year to restrict the number of immigrants.

The 1st Preference applies to unmarried children over the age of 21 of U.S. citizens. 2nd Preference applies to spouses and unmarried sons and daughters of lawful permanent residents. 3rd Preference applies to married children of U.S. citizens and the 4th Preference to siblings of U.S. citizens.