In this episode of "The Race Gap in the U.S.," correspondent Jason Motlagh takes us on a journey with a cast of characters comprised of activists, retired border patrol officers, lawyers and migrants. 

Lewis Arthur is the founder of Veterans on Patrol, a volunteer militia that patrols the Sonoran Desert for undocumented migrants. Arthur insists he's not a racist – but on a mission to stop Mexican cartels that exploit migrants for sex-trafficking and drug running.