Mexican-US illegal migration has been largely static since the 1950s

 
Princeton's alumni magazine has an excellent profile of Douglas Massey, Henry G. Bryant Professor of Sociology and Public Affairs and director of Princeton’s Office of Population Research. Massey studies patterns of US migration, particularly illegal immigration from Mexico. His research is the only rigorous census of Mexican-American illegal immigration flows, and its conclusions are that the US perception of Mexican migration is completely backwards, and that the major immigration problems are the result of bad policy, not changes in volume:

The MMP’s reports are freely available to anyone through its website, http://mmp.opr.princeton.edu. But statistics can be sterile things. Get Massey going, and one gets an earful about the true state of affairs along the border. To wit: * We are not being flooded with illegal Mexican migrants. The total number of migrants from Mexico has varied very little since the 1950s. The massive influx many have written about never happened. * Net illegal migration has stopped almost ­completely. * Illegal migration has not stopped because of stricter border enforcement, which Massey characterizes as a waste of money at best and counterproductive at worst. * There are indeed more undocumented Mexicans living in the United States than there were 20 years ago, but that is because fewer migrants are returning home — not because more are sneaking into the country. * And the reason that fewer Mexican citizens are returning home is because we have stepped up border enforcement so dramatically. Mull over that last point for a minute. If Congress had done nothing to secure the border over the last two decades — if it had just left the border alone — there might be as many as 2 million fewer Mexicans living in the United States today, Massey believes.