New conditions were increasing the growth of the North and West, and their separation from the South in national life, even when nullification was in its death struggle. The acquisition of Louisiana in 1803 had been followed in 1807 by Fulton's invention of the steamboat, the most important factor in carrying immigration into the new territories and opening them up to settlement. But the steamboat could not quite bridge over the gap between the Alleghanies and the Mississippi. Internal improvements, canals, and improved roads were not quite the instrument that was needed. It was found at last in the introduction of the railway into the United States in 1830-32. This proved to be an agent which could solve every difficulty except its own. It could bridge over every gap; it could make profit of its own, and make profitable that which had before been unprofitable. It placed immigrants where the steamboat, canal, and road could at last be of the highest utility to them; it developed the great West with startling rapidity; it increased the sale of government lands so rapidly that in a few years the debt of the United States was paid off, and the surplus became, for the first time, a source of political embarrassment. In a few years further, aided by revolutionary troubles in Europe, immigration became a great stream, which poured into and altered the conditions of every part of the North and West. The stream was altogether nationalizing in its nature. The immigrant came to the United States, not to a particular State. To him, the country was greater than any State; even that of his adoption. Labor conditions excluded the South from this element of progress also. Not only were the railroads of the South hampered in every point by the old difficulty of slave labor; immigration and free labor shunned slave soil as if the plague were there prevalent. Year after year the North and West became more national in their prejudices and modes of thought and action; while the South remained little changed, except by a natural reactionary drift toward a more extreme colonialism. The natural result, in the next period was the development of a quasi nationality in the South itself. The introduction of the railway had brought its own difficulties, though these were not felt severely until after years. In the continent of Europe, the governments carefully retained their powers of eminent domain when the new system was introduced. The necessary land was loaned to the railways for a term of years, at the expiration of which the railway was to revert to the State; and railway troubles were non-existent, or comparatively tractable. In the United States, as in Great Britain, free right of incorporation was supplemented by what was really a gift of the power of eminent domain. The necessary land became the property of the corporations in fee, and it has been found almost equally difficult to revoke the gift or to introduce a railway control.