The permanent checkpoint is on Highway 90 a few miles north of Huachuca City, just north of the intersection with Highway 82. Smugglers drop off illegals on Highway 82, turn on to Highway 90, pass through the checkpoint with only a cursory check, continue up Highway 90 to a point over the hill from the checkpoint, and pick up the illegals. I've seen dozens of illegals at a time running down a well worn path coming out of the desert there.
America's Most Wanted did a show about this last year. They found that a lot of times gangs from Tucson and Phoenix are hired to come down and pick up these illegals after the coyotes have dropped them off. Apparently there's a lot of money to be made in smuggling these invaders.