The lifetime of many and many a man has covered a period longer than that interval of eighty-six years between 1783, when George Washington had his vision of "the vast inland navigation of these United States," and the year 1869, when the two divisions of the Union Pacific were joined by a golden spike at Promontory Point in Utah. In point of time, those eighty-six years are as nothing; in point of accomplishment, they stand unparalleled. When Washington's horse splashed across the Youghiogheny in October, 1784, the boundary lines of the United States were guarded with all the jealousy and provincial selfishness of European kingdoms. But overnight, so to speak, these limitations became no more than mere geometrical expressions. "Pennamite," "Erie," and "Toledo" wars between the States, suggesting a world of bitterness and recrimination, are remembered today, if at all, only by the cartoonist and the playwright. The ancient false pride in mock values, so cherished in Europe, has quite departed from the provincial areas of the United States, and Americans can fly in a day, unwittingly, through many States. Problems that would have cost Europe blood are settled without turmoil in the solemn cloisters of that American "international tribunal," the Supreme Court, and they appear only as items of passing interest in our newspapers. In unifying the nation the influence of the Supreme Court has been priceless, for it has given to Americans, in place of the colonial or provincial mind, a continental mind. But great is the debt of Americans to the men who laid the foundations of interstate commerce. No antidote served so well to counteract the poison of clannish rivalry as did their enthusiasm and their constructive energy. These men, dreamers and promoters, were building better than they knew. They thought to overcome mountains, obliterate swamps, conquer stormy lakes, master great rivers and endless plains; but, as their labors are judged today, the greater service which these men rendered appears in its true light. They stifled provincialism; they battered down Chinese Walls of prejudice and separatism; they reduced the aimless rivalry of bickering provinces to a businesslike common denominator; and, perhaps more than any class of men, they made possible the wide-spreading and yet united Republic that is honored and loved today. BIBLIOGRAPHICAL NOTE