More than 100 miles north of the U.S.-Mexico border, Interstate 8 runs through the mostly untouched Sonoran Desert National Monument. Back in 2010, in addition to cacti, flowers and three distinct mountain ranges, motorists traveling along I-8 also saw signs posted by the Bureau of Land Management, informing them that they had entered an “active drug smuggling area” and might encounter “armed criminals and smuggling vehicles traveling at high rates of speed.”

“Mexican drug cartels literally do control parts of Arizona,” Pinal County Sheriff Paul Babeu told reporters at the time. “They literally have scouts on the high points in the mountains and in the hills and they literally control movement.”