Yuma, Arizona(CNN) Under the shadow of the border wall, dozens of migrants raced to get in line as they spotted the glimmer of vehicle lights down the road. US Border Patrol agents were on the way.
For hours, migrants, primarily of the middle-class in South America, had waited to turn themselves in to the Border Patrol, setting up fires just feet from the border wall to keep warm.
"My family depends on me," said Carlos Garcia, a 47-year-old from Venezuela seeking asylum in the US, in Spanish.
Thousands of migrants have descended on this part of the US-Mexico border in recent weeks, overwhelming facilities and stressing already-taxed resources in the region.
It's the latest challenge for the Biden administration, which for months has been grappling with large numbers of migrants at the US-Mexico border. In October, Border Patrol arrested nearly 22,000 people crossing the border in Yuma, a 1,200% increase from January, according to US Customs and Border Protection data.
At a break along the US-Mexico border wall, migrants, pulling suitcases and carrying luggage, cross and congregate to be picked up by Border Patrol agents. Unlike previous migrant surges, these people -- in many cases -- are middle-class families, underscoring the economic and political instability in much of Latin America.
Francisco Lopez, a 50-year-old from Nicaragua, never planned to migrate to the United States. But political oppression in his home country left him no choice, he said.
"Unfortunately, I had to take this option that perhaps isn't what I had planned for my future," he said in Spanish. Lopez, an attorney, journeyed north with his 18-year-old son.
"On one hand, Covid and the accompanying recessions left many people in the Latin American middle class a lot worse off and people who would not have considered migrating have decided it's a useful option," said Andrew Selee, president of the Migration Policy Institute. "At the same time, the ease of crossing the border has made some people who have ties to the US decide it's time to come now if they're going to make it. I think both those things are true at the same time."
The coronavirus pandemic exacerbated deteriorating conditions in Central and South America, prompting people to journey north. Authorities in South America have been monitoring the increased movement of migrants in the region for months.
Earlier this year, the surge of Haitians -- many of whom had been living in South America for years -- into Del Rio, Texas, served as example of the difficulty in tackling migratory flows that are constantly changing. Those migrants largely made their way on foot and bus.
But many migrants fleeing conditions in Latin America and arriving in Yuma took a different path -- often flying to an airport in Mexico and then crossing at a gap along the Colorado River, cutting the journey down to just days. It's the most viable option for many Venezuelans and Brazilians, for example, who can't obtain a visa that allows them to work in the US -- or can't afford the years-long wait for the legal immigration process.
Yuma Mayor Douglas Nicholls recently issued a local emergency to help the situation in his city. "This is highly unusual. This is ground we've never really tread before," he told CNN.
The Biden administration is expected to send more than 100 agents to Yuma this week to provide additional assistance, according to Nicholls, who's been in touch with the Department of Homeland Security.
In a statement, CBP spokesperson John Mennell said it's working with partners to "expeditiously transport, screen and process those encountered."
"CBP deploys Border Patrol agents and CBP officers as needed to support operations based on fluctuations as necessary. Our borders are not open. CBP stands read to address any scenario as we work to ensure the safety and security of our borders, and to manage a fair and orderly immigration system," the statement continued.
The administration has relied on a Trump-era public health order to swiftly remove thousands of migrants, but there are some nationalities, like South Americans, that aren't accepted by Mexico and therefore largely can't be expelled.
"We're busy everywhere. We're not slow in any specific location. So when you take resources from another location, another busy location, you're just depleting those resources to deal with an issue that can be dealt with through policy," said Brandon Judd, the president of the National Border Patrol Council, adding that smugglers and cartels contribute to the greater number of migrants crossing along parts of the US southern border.
To assist the Border Patrol, Arizona's Department of Public Safety is patrolling a vast area of desert along the border at the request of Republican Gov. Doug Ducey.
"Out here, we're watching the desert, watching for movement, looking for any signs that we have a group coming through," said Major Damon Cecil, chief of staff of the criminal investigations division, referring to the 75-mile stretch that they're monitoring for any criminal activity.
Cecil and his troopers try to fill in the gaps, while the Border Patrol processes the thousands of migrants who are turning themselves over and claiming asylum.
"What we're seeing here is a surge of illegal drugs ... because Border Patrol is tied up and they know manpower out here is limited," Cecil said, referring to smugglers. DPS is seeing more dangerous drugs in larger quantities.
Homeland Security Secretary Alejandro Mayorkas, meanwhile, has repeatedly cautioned migrants against journeying to the US southern border.
"I cannot communicate this message too strongly that individuals should not put their life savings in the hands of smuggling organizations that exploit their vulnerability," Mayorkas said during a news conference last week. "The border is not open."
But for the migrants here, crossing into the United States, they say, is their best shot.
"We have no option but to wait because we've already waited so many years," Garcia said.