In the mid-1980s two very large steamship lines, Evergreen Marine Corporation and United States Lines, inargurated round-the-world (RTW) container ship service. The concept of tying together major transoceanic trade routes in a complete global network is feasible provided that the cargo volumes and freight revenues are sustainable. United States Lines employed enormous new container ships in their one-directional RTW service while Evergreen used frequent sailings of somewhat smaller vessels both eastbound and westbound in their RTW service. United States Lines, unfortunately, was unable to obtain sufficiently high load factors or enjoy sufficient economies of scale to survive whereas Evergreen, emphasizing their high quality service, not only survived but have continued their successful operations to this day.