John H. White, Jr., replies : I was mistaken in stating that steampower was dominant on U.S. railroads as late as 1955. According to Census Bureau statistics, the numerical balance in favor of steam was last held in 1951, when 22,590 steamers and 19,014 diesels were in service on U.S. railroads. By 1955 that balance decidedly favored the “growlers,” when 26,563 diesels and 6,266 steamers were listed. However, I did not state that the conversion from the old form of locomotive to the new form took place between 1955 and 1960. Mr. Nelson either misread or misinterpreted my text. Nor is he correct in asserting that a rapid conversion began following the 1939 EMD freight-diesel demonstration. The railroad industry had by this date exhibited a mild enthusiasm for diesel switching engines, but freight and passengers remained solidly in the domain of King Steam. In 1941, two years after the EMD tour —a success wildly proclaimed by the manufacturer but considerably less enthusiastically received by the railroad industry—orders for new freight diesels were modest. At this time, 12 percent of the switching, 7.7 percent of the passenger work, and a meager 0.2 percent of the freight haulage was performed by diesels. By the end of World War II the skepticism of the railroad industry had begun to give way, and during the late 1940s many major railroads announced plans to go to diesel. The Santa Fe was an early convert because of its water-supply problems; steamers were thirsty beasts, consuming about a hundred gallons per mile, and the problem of obtaining large supplies of suitable water in a desert setting is easy to understand. The good performance of these Santa Fe units demonstrated the diesel as a reliable form of power for the punishing trade of railroading.

The diesel locomotive has proved itself a remarkably efficient servant on railways worldwide, and it has been credited as the salvation of American railroads in the postwar era. At the same time, care must be taken not to denigrate the steam locomotive as a hopelessly inefficient anachronism that should have seen sent to the boneyard decades before its demise in 1960. These machines might not match their successors in terms of thermal efficiency, but they were powerful, rugged, and reliable, and were an indispensable element in the American economy for 125 years.