The pressure on the frontier line had increased steadily during these thirty years. Population moved easily and rapidly after the Civil War. The agricultural states abutting on the line had grown in size and wealth, with a recognition of the barrier that became clearer as more citizens settled along it. East and south, it was close to the rainfall line which divides easy farming country from the semi-arid plains; west, it was a mountain range. In either case the country enclosed was too refractory to yield to the piecemeal process which had conquered the wilderness along other frontiers, while its check to expansion and hindrance to communication became of increasing consequence as population grew. Yet the barrier held. By 1850 the agricultural frontier was pressing against it. By 1860 the railway frontier had reached it. The former could not cross it because of the slight temptation to agriculture offered by the lands beyond; the latter was restrained by the prohibitive cost of building railways through an entirely unsettled district. Private initiative had done all it could in reclaiming the continent; the one remaining task called for direct national aid. The influences operating upon this frontier of the Far West, though not making it less of a barrier, made it better known than any of the earlier frontiers. In the first place, the trails crossed it, with the result that its geography became well known throughout the country. No other frontier had been the site of a thoroughfare for many years before its actual settlement. Again, the mining discoveries of the later fifties and sixties increased general knowledge of the West, and scattered groups of inhabitants here and there, without populating it in any sense. Finally the Indian friction produced the series of Indian wars which again called the wild West to the centre of the stage for many years. All of these forces served to advertise the existence of this frontier and its barrier character. They had coöperated to enlarge the railway movement, as it respected the Pacific roads, until the Union Pacific was authorized to meet the new demand; and while the Union Pacific was under construction, other roads to meet the same demands were chartered and promoted. These roads bridged and then dispelled the final barrier.