On the other hand, the extravagant promises of economy from large trainloads have been considerably abated of late. It has been effectively demonstrated that there is a limit to such growth. Only low-grade and long haul carload traffic can profitably be concentrated. In 1903, for instance, a general decrease in trainloads followed a reduction in the relative amounts of low as compared with high grade tonnage. Less iron, coal, and raw materials and more merchandise and manufactures offered for carriage, necessitated a positive reduction in the trainloads as already mentioned. Nor can local business in less than carload lots profitably be concentrated beyond a certain point. Grades must be uniform to attain such economy. The trainload must not exceed the traction power on the heaviest inclines, or else expensive pusher engines or breaking up of trains will offset all other savings. Moreover, too great trainloads even on the best roadbeds involve slower speeds. Not only is other traffic thus impeded, but the economy in wages vanishes after a certain point with such slower movement. The fashion had been set by James J. Hill, the master mind in the transcontinental field. His notable results, due to a careful working out of every detail, led to a frenzied imitation on all sides. Many roads then discovered to their loss that while they had provided rolling stock for heavy loading, ampler terminals, longer sidings and heavier bridges also were a necessary accompaniment. Part of the congestion of traffic in 1906-1907, already mentioned, and a portion of the financial embarrassments of recent years, were undoubtedly due to too great haste in seeking economies of this sort in rolling stock, without at the same time making provisions for enlargement of other portions of the plant. A more discriminating policy has consequently resulted of late. Traffic is being sorted according to its availability for concentration. The best utilization of the rails and terminals is being more considered. Business demands for quick delivery also enter into the calculation. Instead of a few huge slow-moving leviathans blocking other trains, the line may perhaps better be kept full of many smaller trains moving more nearly together. Such are certain of the details now being worked out. None of them, however, weaken the main proposition that a discriminating concentration of traffic conduces very greatly to economy of operation.