I was vaguely aware that the Interstate Highway System was seen as important for civil defense in the Atomic Age, because dispersed industry would be harder to take out with a limited number of atomic bombs, but the Federal Highway Administration‘s own history points to a slightly different concern:
For the President, the Formosa crisis illustrated the need for the Interstate System. He worried about evacuating Washington and other cities in the event of a nuclear attack. He knew the present roads were inadequate for that purpose. Still, in a meeting with legislative leaders on January 11, 1955, the Formosa crisis prompted a discussion of what would happen in the event of a nuclear attack on the United States. The President said he was worried about an atomic bomb attack, which prompted him to suggest the need for a plan to relocate Congress in an emergency.
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[Civil Defense Administrator Val Peterson told a Senate Armed Services Subcommittee that] evacuation was the only practical solution. “It’s much better to get people out, even if in the process you may kill some of them or damage property. It’s better to do that than to have millions of Americans just stay there and be killed.”
On this same day, Governors Averell Harriman (New York), Robert B. Meyner (New Jersey), and Abraham A. Ribicoff (Connecticut) met with Mayor Robert Wagner of New York City to discuss plans for evacuating the city in the case of a hydrogen bomb attack. A report by the Mayor’s Special Committee on Civil Defense estimated that 1 million people could be moved from the worst danger zones in an hour by rail, subway, and ferryboat. Another 4 million would have to be evacuated by bus, taxi, truck, and automobile along 200 outgoing traffic lanes.
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The report also estimated that 400,000 people an hour could be moved out of Manhattan in 75,000 to 100,000 available vehicles, aside from mass transportation facilities. In addition, if evacuation was not possible, 2,411,855 people could be accommodated on subway platforms serving as emergency shelters.
As illustrated by these activities on the day of General Clay’s testimony, the idea of evacuating cities was by no means unusual. Still, doubt existed about whether evacuation would prove to be practical if needed. In questioning General Clay, Senator Pat McNamara (D-MI), who was from Detroit, observed that when one crash occurs on a freeway, 10 cars pile up. “This is just normal driving, and they are not running scared for their lives.” He couldn’t “visualize it lasting for 10 minutes as a means of escape” and said he would “use the alleys rather than use the superhighway” in the face of a pending atomic attack.
The Interstate Highway System does not strike me as a system for evacuating cities. That does present an interesting thought experiment though: what would be a good system for evacuating a city and getting its population out of immediate danger from the blast and then the fallout? Subways out into the countryside?
This Treehugger piece presents the more familiar argument that one of the best defences against nuclear bombs is sprawl:
In 1945, the Bulletin of the Atomic Scientists began advocating for “dispersal,” or “defense through decentralization” as the only realistic defense against nuclear weapons, and the federal government realized this was an important strategic move. Most city planners agreed, and America adopted a completely new way of life, one that was different from anything that had come before, by directing all new construction “away from congested central areas to their outer fringes and suburbs in low-density continuous development,” and “the prevention of the metropolitan core’s further spread by directing new construction into small, widely spaced satellite towns.”
But the strategy had to change after the development of the more powerful hydrogen bomb, and with it the realization that having people living in the suburbs but working downtown was a problem. “President Dwight D. Eisenhower instead promoted a program of rapid evacuation to rural regions. As a civil defense official who served from 1953 to 1957 explained, the focus changed “from ‘Duck and Cover’ to ‘Run Like Hell.’”
To service that sprawl and to move people quickly in time of war, you need highways; that is why the bill that created the American interstate highway system was actually called The National Interstate and Defense Highways Act of 1956- they are exactly that, defense highways, designed to get people outta town in a hurry.
It’s clear that the suburban way of life didn’t develop because suddenly people could afford cars; it happened because the government wanted it.
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After getting the people out, the next step was to actually move the industries and offices out of the dense urban cores, where so many corporations could be taken out with a single bomb, and establish them in suburban corporate campuses where just about every one of them would be a separate target. There was actually a National Industrial Dispersion Policy, designed to decentralize industry and commerce.