In this Nov. 15, 2013 file photo, Amanda Beverly, of Newfoundland, Canada, looks over souvenirs in Tijuana, Mexico.  To many Republican presidential contenders in Thursday, Aug. 8, 2015 debate, the U.S. border with Mexico must be secured for millions in the country illegally to stay. To many commuters at the nation’s busiest crossing, their border already is secure – even thriving by historical standards. (AP Photo/Gregory Bull)