The Federal-Aid Highway Act of 1956, signed by President Eisenhower, authorised construction of a 41,000-mile (later expanded) Interstate Highway System, with the federal government covering 90 per cent of costs through a Highway Trust Fund financed by fuel taxes. Many of the new freeways were routed directly through dense city cores, requiring extensive demolition. It was the largest public-works programme in American history to that point. The legislation framed the network partly in terms of defence and economic mobility.
By massively subsidising long-distance road building while routing highways through downtowns, the Act hard-wired automobile dependence and suburban sprawl into American settlement patterns. It accelerated central-city decline and disproportionately displaced poorer and minority neighbourhoods in the path of the roads.