The issuance of an immigrant visa requires processing by the USCIS, NVC and United States embassy or consulate. The Immigration and Nationality Act (INA) limits the number of family based immigrant visas that are issued each year based on a preference category. Each preference category is assigned a number of immigrant visas. In addition, there is a limit to the percentage of immigrant visas that can be allotted to each country in a year. Since the demand for immigrant visas is higher than the limited number and greater for some countries, an immigrant visa ‘waiting list’ forms. As such, your foreign relative’s preference category and country of origin will determine the time the relative petition will remain at the NVC until an immigrant visa number becomes available. The wait time can be years.