Why was it inefficient to leave highway construction to individual states?

Leaving highway construction to individual states was inefficient because it led to a lack of coordination and standardization across state lines, resulting in inconsistent infrastructure quality and safety standards. Each state prioritized its own needs, often neglecting regional connectivity and creating gaps in the national transportation network. This fragmented approach also wasted resources, as states might duplicate efforts or invest in projects that didn't align with broader national transportation goals. Overall, a unified federal approach was necessary to ensure a cohesive and efficient highway system.