In pictures: The surge at the US-Mexico border

Migrants cross the Rio Bravo to return to Ciudad Juárez, Mexico, on Saturday, May 13, as members of the Texas National Guard extend razor wire at the border.

Alison, a 6-year-old migrant from Honduras, stands with her mother while they wait to be transported to a US Border Patrol processing facility in La Joya, Texas, on May 13.

US Border Patrol agents watch over migrants waiting to take a bus to a processing center in Fronton, Texas, on Friday, May 12. The migrants had turned themselves in after crossing from Mexico.

A group of men from El Salvador are detained by US Border Patrol agents after crossing the border near Sunland Park, New Mexico, on May 12.

Migrants waiting to apply for asylum near San Diego reach through a border wall for clothing handed out by volunteers on May 12.

A US Border Patrol agent searches a man from Mexico who crossed the border illegally near Sunland Park on May 12.

Ligia Garcia and her husband, Robert Castellon, walk with their children to buy food after they were processed by US border officials in McAllen, Texas, on May 12.

Paula, a woman from Guatemala, holds her daughter as she asks US border officials about the new asylum rules at the San Ysidro Port of Entry, between San Diego and Tijuana, Mexico, on Thursday, May 11.

Migrants in Matamoros, Mexico, gather on the banks of the Rio Grande as they get ready to cross the border to turn themselves in on May 11.

Merejido Del Orbe, who came to the United States from the Dominican Republic, rests at Annunciation House, a shelter in El Paso, Texas, on May 11. He broke his leg when he slipped from a rope while climbing a border fence in April.

Texas National Guard soldiers place more razor wire on the banks of the Rio Grande in Matamoros on May 11.

Migrants from Peru react after crossing the border in Yuma, Arizona, just a few minutes before the lifting of Title 42 on May 11.

As the sun sets on May 11, migrants wait to be processed by US Border Patrol agents across the border from El Paso.

Migrants released by US border officials are seen at a cell phone charging station at the Regional Center for Border Health in Somerton, Arizona, on May 11.

Migrants surrender to the US Border Patrol in Yuma on May 11.

Erick Torres and his son Benjamin, migrants from Peru, wait to be processed by US Border Patrol agents in Yuma on May 11.

Migrants climb onto an air mattress in Matamoros to prepare to cross the Rio Grande toward Brownsville, Texas, on May 11.

Migrants board a bus after surrendering to US Border Patrol agents in Yuma on May 11.

A US Border Patrol agent looks on as migrants wait to apply for asylum near San Diego on May 11.

Norma Garcia Bonilla, from Michoacán, Mexico, waits at Albergue del Desierto, a migrant shelter in Mexicali, Mexico, across from the California border, on Wednesday, May 10. She is seeking asylum in the United States.

Hundreds of migrants in Ciudad Juárez wait to cross into the United States on May 10.

Migrants carry a baby in a suitcase across the Rio Grande on May 10.

A migrant tears up behind a border wall near San Diego on May 10.

Members of the Texas National Guard are deployed to an area of high migrant crossings in Brownsville on May 10.

Wendy Velasquez and her 21-month-old daughter, Starley Dominguez Velasquez, have been living for five months at the Albergue del Desierto migrant shelter in Mexicali. They came from Honduras to apply for asylum in the United States.

Migrants wait to get paid after washing cars at a gas station in Brownsville on May 10. They had arrived the day before from Mexico.

Migrants surrender to US Border Patrol agents after crossing the border in Yuma on May 10.

Migrants cross the Rio Grande from Matamoros on May 10.

Migrants gather between primary and secondary border fences near San Diego on May 10.

Migrants stand in line as they wait to be processed by US Border Patrol agents in Brownsville on May 10.

A migrant climbs over a border wall separating Tijuana from the United States after fetching groceries for other migrants who were waiting to be processed by US authorities on May 10.

A heart-shaped keychain with a photo of Salvadoran migrant Danilo Ruiz and his family hangs from a handbag at a makeshift shelter in Reynosa, Mexico, on Tuesday, May 9.

Migrant families cross into El Paso from Mexico on May 8.

A US Border Patrol agent watches over migrants who had gathered in San Diego on May 8.

A woman is helped off a freight train after she became too scared to climb down from the roof on May 7. Migrants have been traveling on top of freight trains as they headed north from southern Mexico. The woman's son, Leonardo Luzardo, told CNN it had been a long, cold night atop the train, feeling like their bodies were turning to ice. "It seemed like we were going to freeze," he said.

Migrants who were trying to evade US Border Patrol agents wait to be processed in Granjeno, Texas, on May 4.

Children play soccer at a shelter in Tijuana on May 3. Their families were awaiting the end of Title 42.

Migrants camp out in an alley behind the Sacred Heart Church in downtown El Paso on April 30.

Migrants wait to be processed by US Border Patrol agents in Santa Teresa, New Mexico, on April 26.