Driving south on El Paso’s Texas Highway Loop 375, which hugs the Rio Grande, I caught sight of something that’s become familiar to the city’s residents: a massive, eight-wheeled armored vehicle with a turret at its center and a large American flag flying above it. It’s one of the Stryker military vehicles lined up along the border wall in El Paso, looking down into Mexico. Because they have wheels instead of treads, Strykers aren’t technically tanks—in some ways, they’re more intimidating. They can reach over 60 miles per hour while carrying heavy armor, making them more nimble than hulking M1 Abrams tanks. Though I’d soon find out the Stryker I saw was unarmed, the vehicles are designed to carry real firepower: tank guns, cannons, guided…