In order to be eligible for a green card, you must fall into one of the categories below. Some categories receive more preference than others. Since the demand for green cards is always greater than the number of cards available, people who apply under categories with a low preference will have to wait longer than those who are eligible under high-preference categories.

Each year, 140,000 green cards are available to people with job skills that are under-serviced and needed in the U.S. Generally, you need to have a job lined up before you apply, but if there is a workforce shortage in your skill set, you might be accepted without being sponsored by an employer.

The number of green cards issued is limited and if there are more applicants than green cards, you will be placed on a waiting list - whether you have a job lined up or not. The U.S. government gives preference to certain job categories; thus if you're skilled in a low-preference area, your wait will be longer than someone skilled in a high-preference area. Currently, priority is given to:

Sometimes green cards are available for people who have unique circumstances. Although the requirements can change, currently special immigrants include.

If you are in danger of persecution or have been persecuted in your home country, the U.S. government may offer you refuge. Coming from an extremely poor country or an area suffering from random violence doesn't qualify you, however. The persecution must be based on:

Both offer protection, but you apply for refugee status if you are outside the U.S. , and for political asylum is you're already in the U.S.

Because this protection is in response to changing circumstances, the answers will change. Some countries will be added, while others will be removed from the list. Current information can be found at the USCIS site.

In addition to applying for removal of the conditions, Green Card holders married to U.S. citizens are required to attend an immigration interview. The couple must prove that they living together as husband and wife. The purpose of the interview is to verify that the marriage was entered in good faith and not for the purpose of obtaining immigration benefits. The requirement for marital interviews to take place following two years of marriage was created by Congress in 1986. By requiring those that received Green Cards through marriage to attend an interview, the USCIS aims to discover fake marriages that were entered into for economic, business or immigration purposes. 

Individuals who obtained a conditional Green Card through Investment have to prove that the investment and business is viable. Evidence that may be required include tax returns, audited financial statements, and other business documents. 

The time spent abroad does not count towards the residency requirement. However, Green Card holders may submit the "Application to Preserve Residence for Naturalization Purposes." For more information about traveling with a Green Card and how to apply for a Reentry Permit, it is recommended to order the Reentry Permit for Green Card Holders Application Guide. 

The Remove Conditions on Permanent Residence Application Guide contains everything one needs to know in order to remain compliant with USCIS regulations governing conditional Green Cards.