The caravan made up of mostly Central American migrants has covered about 45 miles, and has migrant-rights advocates and aid workers traveling with them. The aid workers estimate there could be 1,000 children among the estimated 4,000 migrants battling the weather and exhaustion.

Irineo Mújica, of the immigration advocacy group People Without Borders, estimated there were between 1,000 to 1,200 children in the caravan group.

“It is urgent that the Mexican government attend to the children,” Mújica said.

Laura Benítez with Global Response Management, a humanitarian aid organization, said that children make up about 40 percent of those in the caravan, and those their organization has given medical treatment to.

“The majority are blisters on feet, chafing. The children have some little cuts, scrapes and bug bites. Besides that we’re giving medicine for headaches, muscle pain, also fever and we’re giving [rehydration],” Benítez said.

Thousands of migrants have been waiting in Tapachula near the Guatemala border, as Mexico’s strategy had been to keep the migrants in the south while allowing them to apply for asylum in Mexico. As Mexico’s asylum system has been overwhelmed and the slow process led many to decide it was not worth waiting for, the caravan continues north toward the border seeking refuge.

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The scene is reminiscent of larger migrant caravans in 2018 and 2019 that were also full of families with young children. The caravans have offered a less expensive, albeit much slower, way to migrate for families without the money to pay smugglers. They also carry the advantage of safety in numbers.

José Avila Lagos and his wife Yolanda Melgares bought two strollers in Tapachula before setting out because they’re traveling with their three children ages 6, 9 and 15.

“[The kids] get hot and tired from walking and you have to bring them in this, Avila said, indicating to the stroller. “You have to spend.”

The truck driver said they left Honduras because of poverty. The pandemic had made it harder for him to find work.

Ingrid, a Guatemalan woman who declined to give her last name due to safety concerns, said that she was traveling with her whole family—four adults, eight children and a 5-month-old baby.

“We just can’t cope, with all the kids. We’re from Guatemala, we’ve already been stuck in Tapachula for two months,” she said.

“We need them to give us free passage; we ask the president to have a heart,” Ingrid said while the family rested in the shade of a tree Thursday.

While smaller migrant groups that attempted to walk out of Tapachula recently were broken up by authorities within a couple of days, the current caravan is larger and has been walking since Saturday. Authorities tried to block it from leaving Tapachula that day, but since then have not interfered.

The caravan formed ostensibly as a form of protest and organizers said the goal was to march to Mexico City to pressure the government to resolve the immigration crisis in the south. However, the majority of those walking appear to have their sights set on the United States.

Luis García Villagran, of the Center for Human Dignity, a nongovernmental organization in Tapachula involved in organizing the march, said the plan was to demand everyone receive permanent residency when they arrive in Mexico City.

“I think even I want to go to the United States because of the conditions this country is in, so Joe Biden can embrace me,” Villagran quipped. “Obviously everyone wants to go to the United States.”