American Border Patrol on TunnelsApril 5, 2009
American Border Patrol flies the border from Brownsville, Texas to the Pacific Ocean. Glenn Spencer, head of ABP says there are very few places from El Paso to San Diego where a tunnel can emerge. (Don't try to dig a tunnel under the Rio Grande).
Time Magazine seems to paint the tunnel problem as insurmountable, but a close look would find that it should be a simple matter to tag every potential tunnel exit and deal with them.