three tunnels in this city all designed to reach under the border what ul that exists here and pop up north of the border. the most recent tunnel actually emptied out in this area behind me. it started contractor started deeper inside the city about three-quarters of a mail away from where we are standing right now. >> reporter: there were two tunnels here. >> reporter: they have spent decades patrolling the borderlands of santa cruz county in arizona. they've seen organized crime cartels adapt to every new evolution of border security. >> they have the world's records as far as tunnels are concerned. >> reporter: more than 100-tonne els have been discovered in nogales since 1995. >> it's opportunity. it's very practical for them. the more difficult you make it for them the more creative they will be. >> reporter: that's a lot of tunnels. >> that's a lot of tunnels. at some point wonder if there will be a few sink holes this side of the border. >> reporter: as the trump