ROMA, TX - AUGUST 16: A U.S. Border Patrol agent watches over detained immigrants near the U.S.-Mexico border on August 16, 2016 in Roma, Texas. Border security has become a main issue in the U.S. Presidential campaign, as Republican Presidential candidate Donald Trump has promised to build a wall, at Mexico's expense to fortify the U.S.-Mexico border. (Photo by John Moore/Getty Images)
