A surge in Cuban and Nicaraguan arrivals at the U.S. border with Mexico in December led to the highest number of illegal border crossings recorded during any month of Joe Biden's presidency, authorities said Friday.

The Biden administration on Thursday launched an online appointment system as the only way for migrants to get exceptions from pandemic-era limits on asylum — the U.S. government's latest major step in eight days to overhaul border enforcement.

President Joe Biden opened his visit to the North American leaders summit with a diplomatic gesture that landed well with his host, Mexico's Andres Manuel Lopez Obrador, before the two leaders were to begin Monday talking about weighty matters including immigration, trade and climate change.

Border communities and Border Patrol are preparing for a surge of migrants when Title 42 – which has been used throughout the pandemic to turn people away at the border – is scheduled to expire on Dec. 21.

The surge of migrants at the southern border has included skyrocketing numbers from countries that were barely represented in previous years, presenting a challenge that experts say the U.S. is not equipped to address.

U.S. authorities stopped migrants more than 230,000 times on the Mexican border in October, the third-highest month of Joe Biden's presidency amid growing numbers from Cuba, Nicaragua, Colombia and other countries.

When Wilfredo Molina arrived in the U.S. from his native Venezuela, he told border agents he wanted to go to Miami but didn't have an address. They directed him to what he thought was a shelter in midtown Manhattan but turned out to be a gray office building. Molina was among 13 migrants who recently arrived in the U.S. who agreed to share documents with The Associated Press that they received when they were released from U.S. custody while they seek asylum after crossing the border with Mexico.

As hundreds of migrants line up along an Arizona border wall around 4 a.m., agents try to separate them into groups by nationality.

Arizona Gov. Jan Brewer has responded in federal court to a friend-of-the-court brief filed by Mexico and 10 other Latin American countries regarding the state's new immigration law.