Sustainable Beef employees, formerly employed at Lexington's Tyson plant, exit the school bus that takes them to and from work in North Platte. The bus service is an attempt to allow people who want to stay in Lexington to live there while working in nearby cities. (Molly Ashford/Nebraska Public Media)On a warm Friday in late May, Travis Harvey sat behind the wheel of a big yellow school bus in a packed parking lot. Cottonwood trees sent summer …