"Rich countries have always exercised a gravitational pull over poorer neighbors. The human migration away from poverty, tidal in its enormity, is something no immigration policy or enforcement mechanism will stop. The only twist this time around is that the smuggling networks that crisscross Mexico have now reached south to the client-rich markets of El Salvador and Honduras, two of the poorest and most violent countries in the hemisphere.
If you want a reason for why this tide has taken this particular course you can start in 1994 when President Bill Clinton tried to dam it up with Operation Gatekeeper. The strategy behind the misguided (at best) Operation was to fortify the border and seal off traditional urban crossing points for Mexican migrants in places like El Paso, Tucson, Nogales, and San Diego. Future migrants would then be pushed into such unpopulated, inhospitable areas that they would no longer cross. That assumption turned out to be totally wrong. What took place over the following decades was a balloon effect: squeezing off air at one point does not make it disappear; it only makes it surge into other pockets.
Twenty years later, blockades and border beef-ups have prompted coyotes to forge 3,000-mile van and train rides through seven distinct routes in Mexico—the tributary streams of what is a mighty and unstoppable human river." - Natasha Vargas-Cooper, Aug. 22, 2014.