text: In this Oct. 23, 2018 image, Ana Delia Soto Duarte, who seeks asylum in the United States from her home in Guerrero, Mexico, waits in hopes of hearing her number called to cross the border in Tijuana, Mexico. The first obstacle that migrants in a giant caravan may face if they reach the U.S. border is a long wait in Mexico. To enter through San Diego, the wait in Mexico is a month or longer, spawning an unusual numbering system. (AP Photo/Gregory Bull