Who can apply for a green card?
Normally, people who want to apply for immigrant visas--or green cards--must have a petitioner in the United States. The petitioner may be a family member or an employer. However, employment-based immigration is much more difficult for the majority of foreigners, since it requires the applicant to possess high levels of education or skills that are in short supply in the United States. It also often requires a job offer from a U.S. employer, and proof that U.S. workers are not being displaced.
Which family members in the U.S. can submit a green card petition for you?
For that reason, the more common way that people outside of the United States apply for green cards is through family members. Only certain relatives can qualify as eligible petitioners. The best kind of petitioner to have is a spouse who is a U.S. citizen, or an adult child (over the age of 21) who is a citizen. If you are in this situation, then you have what is known as an "immediate relative" petitioner, and your green card will be "immediately available." This means that, after the Petition for Alien Relative (known as an I-130 petition) is approved, you don't have to wait in line for a visa to become available before scheduling your visa interview with the consulate.
For people who have other family members, such as siblings or parents who are either U.S. citizens or permanent residents, the line for a green card is much longer. The estimated wait times for visa (green card) availability are summarized each month by the Department of State's visa bulletin. The length of the wait will depend on the "preference category" that the person falls under. Depending on the preference category, an applicant may have to wait for only a matter of months, or up to nearly 20 years, for the visa to become available.