Hundreds of migrants from around a dozen countries have left Mexico’s southern border on foot as they attempt to reach the US border.
Some of the group said they hoped to make it to the US border before elections are held in November because they fear that if Donald Trump wins, he will follow through on a promise to close the border to asylum-seekers.
“We are running the risk that permits (to cross the border) might be blocked,” said Miguel Salazar, a migrant from El Salvador.
The app only works once migrants reach Mexico City, or states in northern Mexico.
“Everyone wants to use that route,” said Mr Salazar, 37.
The group left on Sunday from the southern Mexican town of Ciudad Hidalgo, which is next to a river that marks Mexico’s border with Guatemala.
Some said they had been waiting in Ciudad Hidalgo for weeks for permits to travel to towns further north.
Migrants trying to pass through Mexico in recent years have organised large groups to try to reduce the risk of being attacked by gangs or stopped by Mexican immigration officials as they travel, but the caravans tend to break up in southern Mexico as people get tired of walking for hundreds of miles.
Oswaldo Reyna, a 55-year-old Cuban, crossed from Guatemala into Mexico 45 days ago and waited in Ciudad Hidalgo to join the new caravan announced on social media.
He criticised Mr Trump’s recent comments about migrants and how they are trying to “invade” the US.
“We are not delinquents,” he said. “We are hard-working people who have left our country to get ahead in life, because in our homeland we are suffering from many needs.”
