Tyson Foods is closing its beef plant in Lexington, Nebraska, laying off 3,200 workers next month in a town of just 11,000. Nearly a third of the town’s population will be out of work, causing spinoff layoffs in local businesses and threatening to unravel the small town. Workers who bought homes and sent their children to college will be stuck with bills they won’t be able to pay. Hundreds of families may be forced to pack up and leave. Local businesses struggling without enough customers may have to join them. State agencies are responding with the urgency of a natural disaster, but the workers still have no clear plan for what comes next.