If your direct relatives have U.S. citizenship, they can file Form I-130 for family reunification, and after a few years, you can enter the United States as a permanent resident. The waiting times vary depending on the degree of the relationship. Green card holders can reunite with their spouses and unmarried minor children.

Conditions for Family Reunification in the U.S.
As a U.S. citizen, you can file an I-130 petition for:

Your spouse – without a waiting queue.
Your unmarried child under 21 years of age – without a waiting queue.
Your unmarried child 21 years or older – there is a waiting queue, category F1.
Your married child of any age – there is a waiting queue, category F3.
Your sibling (you must be at least 21 years old) – there is a waiting queue, category F4.
Your parent (you must be at least 21 years old) – without a waiting queue.