In this July 12, 2014, photo, Central American migrants ride a freight train during their journey toward the U.S.-Mexico border in Ixtepec, Mexico. The last time so few people were arrested at the country’s borders was 1973, when the Border Patrol recorded just fewer than 500,000 arrests. And the volume of people being arrested at the border remains dramatically lower than the all-time high of more than 1.6 people in 2000. (AP Photo/Eduardo Verdugo)