Julia Hermosa Gamara and her husband and 13-year-old daughter raced through the reeds and bushes along the Mexican side of the border with Arizona, running as fast as they could to make it across the Colorado River and into the United States before Title 42 lifted.

They got to the border wall a few minutes late. As they stood waiting for a bus to take them and about five dozen other migrants into custody, Ms. Gamara, 49, worried that they had missed their window and would be sent back. The Biden administration has said anyone arriving without using a lawful pathway would be presumed ineligible for asylum.

“They’re going to deport us,” Ms. Gamara said, crying and holding her husband’s hand. “They’re not going to let us enter.”

The family said they were fleeing violence and death threats in the Peruvian city of Ayacucho, where security forces recently killed demonstrators. Ms. Gamara said her father had been killed by guerrillas in the 1980s, and she worried her family would be targeted if they were sent back to Peru.

“We had to leave everything — everything, everything, everything,” she said. “If we go back, we’ll be killed.”

The midnight expiration of Title 42 was mostly quiet, with a few late crossings and U.S. officials preparing for what could be a dramatic increase in people trying to enter the United States as the hours or days wear on.

Here are a few scenes at midnight from along the border:

  • At the McAllen-Hidalgo International Bridge leading into Texas, border officials stood at the ready, some of them wearing riot helmets and gear. A small group of weary migrants lined up before them, including a small child in his father’s arms. A boy holding a Gatorade bottle stared at the officers.

  • About 30 minutes after the order’s expiration, near the California border with Tijuana, a border patrol car brought a new group of migrants to the Tijuana camp, likely people picked up along the border. An agent handed Mylar blankets to the young girls and stepping out of the van. Soon after, the people in the camp settled in for the night, wrapping themselves tightly in blankets to keep out the cold.

  • Shortly after Title 42 expired, Brayan Piar of Venezuela walked with other migrants toward the Department of Homeland Security’s makeshift processing center in Brownsville, Texas. Their pants were still wet with mud as they limped along the darkened levee, celebrating their arrival while being ushered along by Border Patrol agents.

Victoria Kim contributed reporting.