The U.S. will reopen four legal U.S.-Mexico border crossings on January 4 as high levels of illegal immigration have receded and freed up personnel, a senior U.S. official said on Jaunary 2.

The U.S. will reopen an international bridge in Eagle Pass, Texas, two crossings in Arizona and another near San Diego, California, the official said during a call with reporters.

U.S. border authorities struggled in December to process migrants as apprehensions reached nearly 11,000 in a single day, which several current and former officials said was near or at a record high.

Mexican and U.S. officials pledged last week to work together more closely to tackle record migration at their shared border after top U.S. officials travelled to Mexico to meet with Mexican President Andres Manuel Lopez Obrador.

Mexican officials have stepped up immigration enforcement in recent weeks, including moving migrants to southern Mexico and resuming deportation flights to Venezuela, a separate senior U.S. official said.

U.S. border authorities arrested an average of 6,400 migrants per day over the past week, according to an internal U.S. government report reviewed by Reuters, a steep decline from the levels before Christmas.

On the call with reporters, one of the U.S. officials cautioned that migrant crossings have historically dropped between Christmas and New Year’s Day. All officials requested anonymity as a condition of the call.

“We have seen over the last year periods of increased encounters and periods of decreased encounters,” the official said. “We will continue to stand ready to respond to these kinds of surges.”

Lawmakers in the U.S. Congress remain in talks over a possible deal that would combine increased border security measures with foreign aid, including military funding for Ukraine, officials said.