1. The Immigrant Visa Number and Priority Date

U.S. immigration law limits the number of immigrant visas that are available every year. This means that even if the USCIS approves an immigrant visa petition for an alien, the alien may not get an immigrant visa number immediately. In some cases, several years could pass between the time USCIS approves an immigrant visa petition and the U.S. Department of State gives the alien an immigrant visa number.

In addition, U.S. immigration law also limits the number of immigrant visas available by country. This means an alien may have to wait longer if the alien comes from a country with a high demand for U.S. immigrant visas. If the number of applicants exceeds the number of visas available under a particular category, that category is considered oversubscribed.

The filing date of the petition is called the applicant's "Priority Date." A visa cannot be issued until the priority date is reached. This means that there may be a lengthy waiting period. Sometimes that period may exceed several years. 

2. Green Card Application for Foreign Spouse outside of United States

Obtaining U.S. permanent residence through marriage to a U.S. permanent resident is a multi-step process. Some of these steps are required to be completed before the foreign spouse enters the U.S., and some can be completed after entering the U.S. For a foreign spouse, determining whether to apply for adjustment of status or consular processing will significantly depend on the location of the spouse.

If married outside the United States, the foreign spouse usually must remain in her or his country until she or he obtains the Green Card. In this case, the U.S. permanent resident needs to file an immigration petition and request that the U.S. Citizenship and Immigration Services to notify a U.S. Consulate in the country where the spouse lives. 

Once the immigration petition is approved, the National Visa Center of the U.S. State Department sends a forms and information package to the permanent resident's spouse, when the visa number is available. After the necessary forms are completed, the spouse goes to the U.S. Consulate overseas to apply for an immigrant visa. On the day that the spouse enters the United States on an immigrant visa, he or she becomes a U.S. permanent resident.

3. Green Card Application for Foreign Spouse within the United States

If the foreign spouse resides in the U.S., it would then be possible to submit a petition for permanent residency and an application for adjustment of status. The papers filed can include applications for employment authorization (EAD) and a travel permit (Advance Parole). The USCIS issues the employment authorization and temporary travel permit early in the process. 

The USCIS may examine identification, wedding photographs, and documents such as tax returns and insurance documents, and interview the couple to establish the legitimacy of the marriage. An affidavit of support from the petitioning spouse is also necessary.

The U.S. permanent resident needs to prove that the marriage was not entered into for the sole purpose of obtaining a Green Card. The burden is on the parties to establish the real marriage. At the same time, the foreign spouse should submit Form I-485 application, Green Card-type photographs, and numerous other USCIS forms, plus USCIS filing fees.