What was the impact of business on public policy from the Civil War to World War I?
It was enormous
After the Civil War, industry and its magnates triumphed. This period was nicknamed the Gilded Age since only the surface was gilded and it could not be called golden. Prosperity did not benefit everyone. The Robber Barons who controlled the corportations which the economy was run by were the masters who had a tremendous impact on public life.
During the Progressive Era, reforms were introduced in order to regulate that hegemony especially under president Roosevelt.