![Border Patrol agent inspects a tunnel near Nogales, Ariz.](/sites/default/files/photo/Drug%20Tunnel%20Crawl-Nogales%2C%20AZ-JD%201200_0.jpg)
A Border Patrol agent inspects a man-made tunnel near Nogales, Ariz. Such tunnels are used to transport drugs under the U.S. border. (photo by Josh Denmark)
A Border Patrol agent inspects a man-made tunnel near Nogales, Ariz. Such tunnels are used to transport drugs under the U.S. border. (photo by Josh Denmark)