Before revision: Besides Southern Pacific, the Baltimore & Ohio, Burlington Northern, Denver & Rio Grande Western, Florida East Coast, Illinois Central Gulf, Louisville & Nashville, Milwaukee Road, Missouri Pacific, Penn Central (under Merchants Despatch Transportation), Rock Island, Seaboard Coast Line, Frisco, and Southern Railway operated Vert-A-Pacs.
After revision: Frisco,Besides Southern Pacific, the Baltimore & Ohio, Burlington Northern, Denver & Rio Grande Western, Florida East Coast, Illinois Central Gulf, Louisville & Nashville, Milwaukee Road, Missouri Pacific, Penn Central (under Merchants Despatch Transportation), Rock Island, Seaboard Coast Line, Frisco, and Southern Railway operated Vert-A-Pacs.