Final answer:
A pivotal step toward centralizing economic power during the Civil War was through the enactment of federal legislation such as the Homestead Act and Pacific Railway Act, which facilitated infrastructural and economic expansion, and the increased mobilization of resources under federal direction.
Step-by-step explanation:
During the Civil War, a major step towards the centralization of economic power in the hands of the federal government was made through legislation such as the Homestead Act and the Pacific Railway Act of 1862. These acts facilitated the westward expansion and the growth of the railroad network, which in turn encouraged national economic development. Additionally, the war resulted in the extension of federal authority to mobilize resources and regulate several economic activities, further shifting the balance of power towards the national government.
The Union victory asserted the national government's authority over the former Confederate states, mandating ratification of the Fourteenth and Fifteenth Amendments as part of the conditions for re-admittance to the Union. This fundamentally changed the relationship between the federal government and the states, privileging the powers of the central federal authority. The influence of federal policy on economic centralization was indeed profound, setting the stage for subsequent industrialization and economic growth in the post-war period.