Members of an 8,000-person migrant caravan were seen clinging to the sides of a train barreling toward the US southern border as they made their way toward El Paso, Texas.

Footage posted online Thursday showed several dozen migrants clinging to the side of the so-called “The Beast” train as it passed through Chihuahua, Mexico.

It is believed the group is traveling to Juarez, Mexico, which is directly across the border from El Paso, where their asylum claims would be processed by Customs and Border Patrol agents and they would be allowed into the US.

The group apparently is hoping to arrive in Texas before a new state law goes into effect that would allow state police to arrest, jail, prosecute and possibly even deport anyone who crosses the border illegally.

The law is set to go into effect in March but is already facing legal challenges from the Biden administration.

A Justice Department official sent a letter to Texas Gov. Greg Abbott on Thursday saying that the law was unconstitutional and “contrary to the US commitment of ensuring the processing of noncitizens consistent with the Immigration and Nationality Act.”

If the state starts to enforce the law, the Justice Department said, it will file a lawsuit.

But the caravan making its way to the US threatens to further strain the already overburdened Border Patrol, which is seeing a record number of border crossings.

There were 242,418 encounters last month, according to the latest figures released by US Customs and Border Protection (CBP) Friday.

December is also on track to reach an all-time high with as many as 10,000 migrants apprehended each day at the southwest border.

The total number of migrant encounters in December has already surpassed 200,000.

In an effort to stem the tide of migrants, US Customs and Border Protection halted railway operations at international crossings into Texas earlier this month.

“CBP is continuing to surge all available resources to safely process migrants in response to increased levels of migrant encounters at the southwest border, fueled by smugglers peddling disinformation to prey on vulnerable individuals,” the agency said in a statement at the time.

“After observing a recent resurgence of smuggling organizations moving migrants through Mexico via freight trains, CBP is taking additional actions to surge personnel and address this concerning development, including in partnership with Mexican authorities.”

But on Thursday, Mexican President Andrés Manuel López Obrador announced that Mexican and American authorities have agreed to keep the border crossings open.

“This agreement has been reached,” he said at a morning news conference.

“The rail crossings and the border bridges are already being opened to normalize the situation.”

Meanwhile, more than 11,000 other asylum seekers are huddled on the Mexican side of the southern border in shelters in camps, awaiting an opportunity to cross over into the United States. 

Roughly 3,800 asylum seekers from Mexico, Haiti, Venezuela and Cuba are gathered in Tijuana, Mexico, CNN reported.

Another group of about 3,723 migrants are biding their time in Reynosa, across the border from McAllen, Texas.

A crowd of 4,000 asylum seekers is also waiting in Matamoros, Mexico, scattered in camps, shelters and abandoned homes.

The migrants who remain in Mexico are hoping to take advantage of a federal parole program introduced by the Biden administration earlier this year and cross legally, according to Glady Cañas, who runs a nonprofit providing services to asylum seekers in Matamoros.

With Post wires