A story of the backbone of America's transportation system - the railroad - this film traces the evolution of locomotive power from steam through electric and diesel-electric to the latest super-powered gas-turbine electric. Emphasis is given to the ways in which these developments have kept pace with the ever-growing demands of a nation that today virtually "lives out of box cars." The picture also offers a glimpse of the operational mechanics of the country's complex railway net¬works—accenting the many applications of electricity. The striking color and the non-technical, human-interest approach combine to give this picture high general-audience appeal.