Impacts of Border Enforcement on Unauthorized Mexican Migration to the United States
Published on: Sep 26, 2006

Wayne A. Cornelius is Distinguished Professor of Political Science, Gildred Chair in US-Mexican Relations, and Director of the Center for Comparative Immigration Studies at University of California, San Diego. He is the author, co-author, or editor of more than 240 publications dealing with the political economy of immigration and immigration policy in advanced industrial nations, Mexican politics, and U.S.-Mexican relations.


How have heightened border controls affected the decision-making of unauthorized Mexican migrants to the United States?1 My research findings, based on highly detailed, face-to-face interviews with 1,327 migrants and their relatives in Mexico during the last 18 months,2 support earlier research showing that tightened border enforcement since 1993 has not stopped nor even discouraged unauthorized migrants from entering the United States.  Even if apprehended, the vast majority (92-97%) keep trying until they succeed.  Neither the higher probability of being apprehended by the Border Patrol, nor the sharply increased danger of clandestine entry through deserts and mountainous terrain, has discouraged potential migrants from leaving home.  To evade apprehension by the Border Patrol and to reduce the risks posed by natural hazards, migrants have turned increasingly to people-smugglers (coyotes), which in turn has enabled smugglers to charge more for their services.  With clandestine border crossing an increasingly expensive and risky business, U.S. border enforcement policy has unintentionally encouraged undocumented migrants to remain in the U.S. for longer periods and settle permanently in this country in much larger numbers.

Drawing on my more than three decades of fieldwork among Mexican migrants to the U.S., and a large body of research by other immigration specialists, I argue that a border enforcement-only (or border enforcement–first) approach to immigration control will only produce more of these unintended consequences while failing to construct an effective deterrent to illegal entry.  If built, the new physical fortifications and virtual surveillance systems included in the immigration bills approved by Congress since last December will have no discernible effect on the overall flow of illegal migrants from Mexico.  But these new layers of protection will give people-smugglers an additional pretext for raising fees; divert clandestine crossings to more remote and dangerous areas, multiplying migrant deaths that are already running at 500-1,000 per year, including undetected bodies; cause more unauthorized crossings to be made through legal ports-of-entry, using false or borrowed documents; and induce more migrants and their family members to settle permanently in this country, thereby increasing outlays for health care and education.

The basic problem with fortifying borders is that it does nothing to reduce the forces of supply and demand that drive illegal immigration. These forces include: (1) the U.S. economy’s persistently strong, and growing, demand for immigrant labor, at all skill levels; (2) extremely limited worksite enforcement, which has had no impact on the demand for unauthorized migrant labor; (3) the very large and still growing real-wage gap between Mexico and the United States (at least 10:1 for most low-skilled jobs); and (4) family ties – over 60 percent of the Mexican population have relatives in the U.S. – which provide a powerful incentive for family reunification on the U.S. side of the border.  

More promising alternatives for reducing unauthorized immigration include a broad, earned legalization program; reducing the need to migrate illegally through significant increases in temporary and permanent visas (especially for low-skilled workers); and a binational program of targeted development to create alternatives to emigration in migrant-sending areas of Mexico.

This essay concludes with a review of the evidence concerning the economic and fiscal impacts of immigration to the United States, including immigration from Mexico, which suggests that current attempts by policymakers to limit access to immigrant labor through border enforcement are short-sighted and not in the national interest. 

Specific Research Findings

Since 1993, the U.S. Government has been seriously committed to reducing the flow of unauthorized immigration from Mexico, through tougher border enforcement.  We have spent more than $20 billion on this project, and we continue to spend at a rate of more than $6 billion a year.  Our strategy since 1993 has been to concentrate enforcement resources along four heavily-transited segments of the border, from San Diego in the west to the South Rio Grande Valley in the east. The logic of this “concentrated border enforcement” strategy is simple:  Illegal crossings will be deterred by forcing them to be made in the remote, hazardous areas between the highly fortified segments of the border.

What effect has this strategy had on the flow and stock of illegal immigrants?

  • When we embarked upon this project in 1993, the Border Patrol was making slightly less than 1 million apprehensions a year.  Thirteen years later, the Border Patrol is making over 1 million apprehensions each year.  
  • The trends in apprehensions and spending on border enforcement intersected in Fiscal Year 2002.  Since then, spending has outpaced apprehensions.

  • During the period of tighter border enforcement, the population of unauthorized immigrants living in the U.S. has more than doubled in size, to something between 11-12 million. 

  • Illegal entries have been redistributed.  Migrants and the people-smugglers who assist them have just detoured around the heavily fortified segments of the border.  
  • When we squeezed the border in the San Diego and El Paso areas, it bulged in central Arizona.  The central Arizona border was reinforced, and since last fall illegal entries have been shifting westward, to Yuma and the California border, and eastward, to New Mexico and the El Paso area.  (San Diego and El Paso had been considered “operationally controlled” by the Border Patrol for the past seven years.)  Most apprehensions are still occurring in central Arizona, but they are up by 21% in San Diego so far this Fiscal Year. 

  • The Border Patrol has reported a 45% drop in apprehensions, borderwide, in the last two months, attributing this to the President’s deployment of National Guard troops.  But apprehensions have fallen by only 2% for the whole Fiscal Year to date, and that could easily turn into an increase for the year if there is a spike in apprehensions during the last three months of the Fiscal Year. 
  • There is no hard evidence to support linking the recent downturn in apprehensions to the presence of National Guard troops on the border.  Anecdotal evidence suggests that the main effect of the deployment has been to drive more migrants into the arms of people-smugglers and enable the smugglers to raise their fees – by $500-1,000 along some segments of the border.
  • Our data show that a higher percentage of unauthorized migrants are being apprehended on a given trip to the border than in the 1980s.  Even so, only about one-third are apprehended.
  • And even if migrants are caught, they keep trying until they succeed.  Our interviews with returned migrants in three different Mexican states revealed that between 92-97% of them eventually succeeded, on the same trip to the border. 
  • If the current U.S. border enforcement strategy were working, we should be seeing that the increased costs and risks of clandestine entry are discouraging prospective migrants even from leaving home. In fact, in our research in Mexican sending communities we have found that three-quarters of would-be migrants are quite knowledgeable about U.S. border enforcement operations.
  • About two-thirds believe that it is much more difficult to evade the Border Patrol now than it used to be.
  • Eight out of 10 believe that it is much more dangerous to cross the border without papers today, and many of the migrants whom we interviewed personally knew someone who had died trying to enter clandestinely.
  • More than two-thirds had seen or heard PSAs warning of the dangers of clandestine border crossings, but fewer than one out of ten said that such messages would have any effect on their plans to migrate.
  • It is difficult to overestimate the determination of the people who are willing to take such risks.  One of our recent interviewees, a 28-year-old father, told us:   “We don’t care if we have to walk eight days, fifteen days—it doesn’t matter the danger we put ourselves in.  If and when we cross alive, we will have a job to give our families the best.”