Sacramento-based Matheson Trucking Inc. and two subsidiaries are in the process of laying all 335 employees in the region and closing their doors after more than six-decades in operation. The company, along with Matheson Postal Services and Matheson Flight Extenders, detailed the layoffs and the shutdown in multiple notices to the California Employment Development Department and Sacramento County. The Matheson entities are large contractors for the U.S. Postal Service transporting mail across the nation.