The decades 1870-1880, 18.--Trans-Mississippi development, 18.--Pacific Coast routes opened, 19.--Development of export trade in grain and beef, 20.--Trunk line rate wars, 21.--Improvements in operation, 23.--End of canal and river traffic, 24. The decade 1880-1890, 27.--Phenomenal railway expansion, 28.--Transcontinental trade, 28.--Speculation rampant, 29.--Growth of western manufactures, 30.--Rise of the Gulf ports, 31.--Canadian competition, 33.--General résumé and forecast, 34. Public land grants, 35.--Direct financial assistance, 37.--History of state aid, 39.--Federal experience with transcontinental roads, 40. The possibility of a unified nation of ninety odd million souls, spread over a vast territory of three million square miles,--three-fourths of the area of Europe,--was greatly enhanced at the outset by the geographical configuration of the continent of North America. It was fortunate, indeed, that the original thirteen colonies were strictly hemmed in along the Atlantic seaboard, thus being protected against premature expansion. At the same time the north and south direction of this narrow coastal strip, with its variety of climates, soils, natural resources and products, brought about a degree of intercourse and mutual reliance of the utmost importance. The mere exchange of the dried fish and rum of New England, for the sugar, tobacco, molasses and rice of the southern colonies, paved the way for an acquaintance and intellectual intercourse necessary to the development of national spirit. Throughout the colonial period, the protected coast waters and navigable rivers as far inland as the "fall line," rendered the problem of long distance transportation relatively easy. For everything went by water. Population was compelled to develop the country somewhat intensively, by reason of the difficulty of westward expansion. But this population after the Revolution began to press more and more insistently against the mountain barriers; so that the need of purely artificial means of transportation at right angles to the seaboard became ever more apparent.