The end of 2018 marks the beginning of work without pay for the approximately 54,000 federal border agents and customs officers who received their last paycheck over the weekend.

Of an estimated 60,000 personnel at U.S. Customs and Border Protection, 90 percent were deemed essential and have been working since Department of Homeland Security funding lapsed Dec. 21, according to a congressional report. CBP would not comment on the exact figure when asked Monday.