Over more than three decades (1946-1978), Pinkerton was a pioneer in the creation, management and use of the short line railroad system in Michigan. He led in making short line railroads the predominant operating mode for all railroad operations outside the state's heavily industrialized areas. In the 1970's he was the first railroader to work with the State of Michigan to preserve service in areas not served by major carriers. Innovations in management and investment enabled his Detroit & Mackinac Railway Company to grow and prosper as the leading carrier in Lower Michigan.