If you have an immediate relative who is a United States citizen, you may apply for a Green Card without waiting. You are an immediate relative if you are: 

• The spouse of an American citizen;
• Unmarried, under the age of 21, and you have at least one U.S. citizen parent;
• The parents of U.S. citizens, if the U.S. citizen child is over 21 years old;
• A stepparent or stepchild. In that case, you qualify as an immediate relative if the marriage which created the parent-child relationship took place before the child's 18th birthday; 
• Related through an adoption if the adoption took place before the child reached the age of 16.