Traffic Up Through Sasabe

Arthur Rotstein of the AP writes: "U.S. Border Patrol officials are seeing a significant increase in the number of illegal immigrants being smuggled through what's known as the Sasabe corridor southwest of Tucson." Why?
Since last summer and fall, areas cutting through the Buenos Aires National Wildlife Refuge, with its diverse vegetation and shorter distances from the border to well-traveled roads in some instances, have gained currency as smugglers try to evade capture by Border Patrol agents.