Expansion of the network of railways in the United States had by 1870 reached a point which made possible large-scale exploitation of the nation's mineral and other natural resources. Swift technological advance and rapid development in business practices followed. The free competition of earlier years gave place in many industries to monopolies or "trusts." Although the total national wealth was increasing, it tended to become concentrated in the hands of relatively few persons. During these same years the flood of immigrants to America swelled to such proportions as to make it the greatest population movement in modern history. The new industrialism, founded upon railway transportation, brought an ever increasing proportion of the population into huge urban centers. Post-Appomattox Americans confronted new and difficult problems.
The rise of industrialism also brought into being a large group of wage earners. Clashes, at times violent and bitter, disturbed the relations between labor and management. An effective alliance between many corporations and political bosses aroused fear that a plutocracy had come into existence. Agrarians, newly group-conscious, challenged the railroads and the other monopolists. In 1896 their crusade, led by William Jennings Bryan, was defeated, partly as a result of the political leadership of Marcus A. Hanna. The revolt of the farmers merged into that of the Progressives. These latter sought to remove the defects of the democratic process, and to curb the power of big business by antitrust laws and by regulatory commissions. Southerners, struggling to build a new economic structure on the ruins of the old, saw before the end of the period the spread of industrialism into their section of the country.
The new technology of the transition age was an obvious triumph for natural science, and the prestige of the scientific disciplines was, at the end of the century, great. The acceptance by America's intellectual world of Darwin's evolutionary hypothesis, synchronizing with swift technological advance, brought disastrous results for the old Protestant orthodoxy. By the close of the century, Calvinism persisted only in rural areas or among the less literate of the city populations. The publication in 1896 of History of the Warfare of Science with Theology in Christendom, byAndrew D. White, may be taken as a convenient date for the defeat of the old orthodoxy. Old Testament criticism had aided in bringing about this overthrow. No longer was it possible to look upon the Scriptures as the literally inspired word of Deity to man, and liberal Protestants, abandoning the old doctrine of inspiration, worked toward new supernaturalistic formulas called Modernism.
To the left of these iconoclasts, a large and growing group, many of whom were inspired by Robert Ingersoll, replaced Christianity by a frank and somewhat sentimental humanism. This view of life, emphasizing the law of love, was often called the Religion of Humanity. Its proponents were, for the most part, motivated by strong humanitarian sentiments. After Appomattox the problem of urban poverty, taking the place which Negro slavery had occupied before the war, absorbed the attention of the humanitarians.