Southern border arrests continue to decline, challenges remain for immigration authorities

The number of migrants stopped by authorities along the southern border continued to fall into the final month of 2019, according to U.S. Customs and Border Protection data released on Thursday.

The decline marks a seven-month low in the number of unauthorized migrants attempting to cross the southern border. Border agents stopped just over 40,000 people in December, down from a peak of more than 144,000 in the month of May.

CBP conducted nearly 50% fewer enforcement actions along the U.S.-Mexico border last month compared to the same time in 2018. This time last year, the elevated numbers were on the verge of ballooning into record-setting levels that strained CBP resources and resulted in heavily overcrowded Border Patrol stations.

"Despite these recent successes we still have a border crisis," a CBP official said Thursday. "It's not over."

Human traffickers continue to shift tactics in attempting to smuggle victims across the border, officials told reporters on Thursday.

As the number of total recorded crossing attempts declined in recent months, the percentage of Mexicans arriving at the border continues to grow, a CBP official said. Acting Homeland Security Deputy Secretary Ken Cuccinelli confirmed on Twitter a BuzzFeed News report that the administration would begin deporting some asylum seekers from Mexico to Guatemala.

The impoverished Central American country signed an agreement with the Trump administration in July to accept asylum seekers from Honduras and El Salvador. ABC News confirmed Homeland Security began flying certain prospective asylum applicants to Guatemala in November.