started deeper inside the city, three-quarters a mile away from where we're standing right now. >> there were two drug tunnels right here. >> reporter: they've spent decades patroling the borderlands of santa cruz county and have seen organized crime cartels adapt to every new evolution of border security. >> we have the world's record as far as tunnels are concerned. >> more than 00 tunnels have been discovered in nogales. >> no buffer zone. the more difficult you make it for them, the more creative they're going to be. >> that's a lot of tunnels. >> that is a lot of tunnels. at some point you wonder if there's going to be a huge sink hole this side of the border. >> as the trump administration pushes to expand the existing border walls, border authorities predict this will force cartels to expand their underground operations. >> we're talking about tunnels, it's linked to the dynamics and economics of the drug trade.