HAMPTON, Iowa — It was quitting time. Edith Rivera took one last lunch order, dropped off a basket of tortilla chips and set off from work, heading out to the farm roads where other immigrants feared to drive.

Like them, Ms. Rivera, 33, had no legal status in the country where she had lived for 18 years. She had no driver’s license, apart from the long-expired North Carolina identification she held safe, like a talisman, in her wallet.

But as she skimmed past the northern Iowa cornfields on her way to her son Steven’s seventh-grade track meet, she did not share other immigrants’ fears. Not of being pulled over. Not of raids or deportation. Not of the man in the White House. Not of the new Franklin County sheriff’s quest to make sure this rapidly diversifying community of hog barns and egg farms would never again be known as an immigrant sanctuary.

Her American journey was waning, and she had little left to lose.

Her husband, Jesús Canseco-Rodriguez, was already gone — deported to Mexico in 2015. Ms. Rivera had jettisoned their apartment and sold off what the family had built here in Hampton: their small business power-washing hog barns, Mr. Canseco’s work truck, their furniture.