“They keep telling us it’s coming tomorrow and the day after, and nothing happens,” said Mr. Nolasco, who has been waiting for a work visa for more than a month. “We just want to get out of here, but they told us we would be detained if we leave.”

The disturbances in the Mapastepec migrant camp have added to a growing wariness among residents here and in other towns in Chiapas that have served as waystations for the caravans in recent months.

“Not all of them are here wanting better opportunities or work,” said Dora Luz García Cruz, a food vendor in Mapastepec. “We are constantly afraid there is going to be a brawl or clashes with the police.”

When municipal officials in Huixtla tried to block about 2,000 migrants from entering the town in recent days, some members of the caravan forced themselves past the police cordon anyway and spent the night in the town center.

“People are just tired of them causing a mess,” said Jonathan Soto, 26, a Huixtla resident.

But many migrants seemed unfazed by the growing public animosity toward them.

Nelson Chirino, a Honduran migrant who was traveling with his 11-year-old son, said he was determined to make it to the United States, even though they had run out of money and were traveling without proper Mexican immigration papers.

”We can’t stop,” he said. “We must push on and never, ever look back.”