My family emigrated from Mexico when I was young. Now an American citizen, I went to the 2014 Border Security Expo in Phoenix, where the newest military technology meant to target people like us is part of a booming industry.

Every few seconds the chatter in the lobby is punctuated by a succession of short, rapid cracks so loud I can feel the concussions in my chest. No one else seems to notice. The Phoenix Convention Center's southern building is packed with hawkish-looking white men in muted suits who somehow continue networking amid the piercing sound. They're all wearing convention badges around their necks that display their ominous affiliations: DOD, DOJ, DHS, Raytheon.

It's the first day of the eighth annual Border Security Expo, where arms dealers and their government buyers come together in a feeding frenzy of defense contracts. There are only so many missile systems one can sell, so companies like Raytheon have found a way to keep revenue flowing with border security. I cut past clusters of men as I make my way toward the crackling, which seems to be coming from beyond the closed doors of the expo hall. I push one of them open just a bit and peek inside.