A storm-water channel connecting the higher-elevation Nogales, Sonora, brings runoff into Nogales, Ariz., and can also deliver illegal immigrants willing to risk drowning when the waters rise.
That's not the only way people come over the border. The easiest is through the fence. The border fence is made of 25-foot-high steel girders and it snakes off into the distance on the hilly outskirts of Nogales (Ariz.). But it's little hindrance to determined smugglers. Border Patrol agents refer to it as a "30-second delay."









