NOGALES, Mexico — One by one, men and women crawled on their knees and bellies across the hot desert sand about 100 yards from where rumbling tractor-trailer rigs crossed from Mexico into Arizona. In temperatures near 100 degrees, they looked like they were on a military reconnaissance mission, but their tattered clothing said these weren't soldiers. They were trying to make their way from southern Mexico to the United States. President Bush and Congress have vowed to seal America's porous border with thousands of National Guard troops, miles of fences, surveillance cameras and aerial drones. But in the Mariposa Canyon,...
