19. How did building the Interstate Highway and Defense System help the U.S. economy? The U.S. military built the roads, leading to more men joining the armed forces. Federal government spending on the supplies and construction of the road kept Americans employed. The new road system was part of the military-industrial complex. State governments imposed a steep tax increase to pay for the highways.

19. How did building the Interstate Highway and Defense System help the U.S. economy? The U.S. military built the roads, leading to more men joining the armed forces. Federal government spending on the supplies and construction of the road kept Americans employed. The new road system was part of the military-industrial complex. State governments imposed a steep tax increase to pay for the highways.