All of these tensions have turned the town into a political battleground, with residents protesting the Biden administration, the governor sending state troopers and residents like Mr. Rodriguez lamenting what has happened to his city.

“No one was prepared for this,” Mr. Rodriguez said. “We won’t be the same after this is over.”…

“This town is too poor, we don’t have the resources,” said Robb Jump, 59, who lives steps away from the river that divides the United States from Mexico.

In anticipation of a possible surge that began with migrants fleeing Central America earlier this year, the state of Texas erected a razor wire-topped chain-link fence on one road, Vega Verde, after residents complained that hundreds were crossing into their land. On Saturday, construction workers added barriers not far from where Dave Rosser, 81, lives.

“They built it too late,” said Mr. Rosser, shaking his head, adding that the city is not designed “to deal with a crisis this big.”