Unauthorized aliens residing in the United States: Estimates since 1986

Estimates derived from the March Supplement of the U.S. Census Bureau's Current Population Survey indicate that the unauthorized resident alien population (commonly referred to as illegal aliens) has risen from 3.2 million in 1986 to 10.3 million in 2004. The estimated number of unauthorized aliens had dropped to 1.9 million in 1988 following passage of a law that legalized many unauthorized aliens. Research suggests that a constellation of factors has contributed to the increase in unauthorized resident aliens, including the "push-pull" of a prosperous economy, the inadvertent consequence of border enforcement policies that have curbed the fluid movement of migrant workers, and the backlogs in processing immigrant petitions. Some observers also assert that resources for enforcement of immigration laws in the interior of the country are inadequate. This report does not track legislation and will be updated as needed.