The Progressive Era
The Civil War increased the power of the federal government by forcing the Southern states to abolish slavery and paved the way for still greater increase in other matters after the war. People expected it to do more, and gave it more power so it could try. The defeat of the South, Reconstruction, and the Supreme Court’s interpretation of the Fourteenth Amendment gave the national government growing power over the states and the people. The great and long-overdue liberating qualities of the Thirteenth, Fourteenth, and Fifteenth Amendments came, ironically, at a price to liberty: the government would need much greater power it if was going to attempt to enforce equality.
Also important to the constitutional history of the United States during this time were developments on the world stage. The ideas of German philosophers Karl Marx and Friedrich Engels captured the attention of intellectuals and many others concerned with the conditions of the poor in industrialized nations.