Final answer:
The most significant public works project under President Eisenhower was the construction of the Interstate Highway System, which was both a critical infrastructure and a national defense project started in 1956.
Step-by-step explanation:
The most significant and largest public works project during President Dwight Eisenhower's administration was the construction of the Interstate Highway System. Initiated in 1956 with the passage of the Federal Aid Highway Act, this grand endeavor was not only a massive civil engineering project but also a crucial component for national defense, as it allowed for rapid movement of military troops and equipment.
Moreover, the interstate system had a transformative impact on American society by accelerating suburbanization and changing the spatial dynamics of cities and suburbs.
Previous public works programs, such as the Public Works Administration (PWA) and the Works Progress Administration (WPA), laid the groundwork for this expansive network of roads. However, the Federal Highway Act was a culmination of efforts to modernize the nation's infrastructure, with President Eisenhower at the helm, drawing inspiration from the German Autobahn to ensure efficient troop movement, something he appreciated following his military service in World War II.
This significant investment in infrastructure symbolized a balance between Eisenhower's dedication to national defense and his caution against unchecked military spending.