Definition
An expressway is a limited-access, grade-separated highway designed to move automobile traffic at high speed across long distances, including across the heart of dense cities. Mid-twentieth-century U.S. policy treated expressways as a generic public good — federal money for state-and-local construction, with little weight given to what was demolished to make room.
In Robert Moses's hands the urban expressway became the defining instrument of his postwar career: thirteen of them in and around New York, most cut through existing neighborhoods, all routed by an administrator whose contempt for transit was matched only by his faith in cars.
Why it matters
How it works
An expressway combines four irreversible commitments: large fixed capital, taking of land by eminent domain, dependence on continued automobile use to justify the investment, and physical division of the area it crosses into "sides." Once built, the highway pushes the surrounding land use to support more cars and more car-dependent users; transit alternatives are starved or shelved.
The dynamic is self-reinforcing. Every expressway built makes the next expressway more politically defensible (the previous one is full) and the alternative — investment in transit — appear less viable (ridership has fallen because the highway absorbed it). The 1960s revolt against urban highways was the recognition that this self-reinforcing loop had a moral cost no one had measured.