From Envirowiki

Post WWII transportation policy has been a major harm to promoting bicycling as transportation.

Segregationist public way design policies, over-engineered facilities built to encourage the public to see high speed roadways that always operate very far from capacity as some kind of birth right, massive subsidy and edicts promoting transportation infrastructure that encourages sprawl development practices, massive subsidies and edicts that dictate one particular expensive, inequitable, inefficient model for commercial transportation...