The border enforcement budget increased 600 percent from 1993 to 2006, allowing the Border Patrol to increase its number of agents from about 4000 to 12,350 over the same period. New fencing and sophisticated surveillance systems have been added to the border amid enthusiasm for increased enforcement from both Republicans and Democrats in Congress.
There is strong evidence that the major effect of enforcement efforts has not been to deter unauthorized migrants, but rather, to unleash a series of unintended consequences. The fees migrants pay coyotes (people smugglers) have increased from several hundred dollars to about $2500 as mom-and-pop coyote operations have become sophisticated networks of operatives on both sides of the border using safe houses, tunnels, falsified papers, and other expensive techniques to move their clients. Concentrated border enforcement in urban areas has indirectly caused the death of an average of one migrant a day as entrants seek to circumvent these fortifications by crossing wilderness areas and rivers and canals with an elevated risk of dying from exposure or drowning. The greatest paradox is that the border policy has bottled up unauthorized migrants in the United States once they have crossed. Unauthorized migrants are increasingly likely to stay in the United States for long periods to pay off the debts they incurred to coyotes and avoid the physical risks and high costs of multiple border crossings. The Department of Homeland Security estimates that between 2000 and 2006, the number of unauthorized Mexican immigrants grew from 4.7 to 6.6 million.