U.S. Postal Service carrier John Graham packs his mail bag after parking a 28-year-old delivery truck, Wednesday, July 14, 2021, in Portland, Maine. The Postal Service’s aging fleet of trucks is soldiering on even as a contract for greener replacement vehicles is being challenged. The primary fleet of vehicles that were delivered starting in 1987 is due to be replaced under a new contract, but the winning bid is being challenged. (AP Photo/Robert F. Bukaty)