In his 1956 State of the Union Address to Congress, President Dwight D. Eisenhower called for “legislation to provide a modern, interstate highway system.” Within months, after considerable debate, Congress passed the Federal-Aid Highway Act of 1956. It authorized the extension of highways nationwide in one of the largest public works projects in U.S. history. Interstate highways made travel and commerce more efficient. They also provided key routes for evacuating urban centers—a critical national defense issue in the Cold War era.