This story about a plane landing on a North Carolina highway reminded me of a myth about the U.S. Interstate system: the idea that they could be used by military aircraft in times of crisis.

Numerous folks swear Interstate highways in the United States must be designed so that one mile in every five is perfectly straight and flat. According to this whispered bit of facetious lore, if the U.S. ever comes under attack, those straight, flat stretches will be used as landing strips.

Belief in this crazy idea should fail anyone’s logic test. It makes no sense to render inoperable the Interstate highway system during times of domestic crisis — moving troops and supplies on the ground would be too important an activity to curtail just to land planes. The U.S. is riddled with any number of small, private airfields that could be pressed into service if the need arose, with that need being dependent on some foreign power having first knocked out an almost uncountable number of major airports plus those airstrips on military bases, not to mention the American fleet of aircraft carriers. Folks who commit to believing this crazy notion of highways doubling by design as airstrips are letting the romance of a “cool fact” blind them to what their common sense should be blinking at them in bright neon letters.

Richard Weingroff, information liaison specialist for the Federal Highway Administration’s Office of Infrastructure and the FHA’s unofficial historian, says the closest any of this came to touching base with reality was in 1944, when Congress briefly considered the possibility of including funding for emergency landing strips in the Federal Highway-Aid Act (the law that authorized designation of a “National System of Interstate Highways”). At no point was the idea kited of using highways or other roads to land planes on; the proposed landing strips would have been built alongside major highways, with the highways serving to handle ground transportation access to and from these strips. The proposal was quickly dropped, and no more was ever heard of it. (A few countries do use some of their roads as military air strips, however.)

Some references to the one-mile-in-five assertion claim it’s part of the Federal-Aid Highway Act of 1956. This piece of legislation committed the federal government to build what became the 42,800-mile Eisenhower Interstate Highway System, which makes it the logical item to cite concerning regulations about how the interstate highway system was to be laid out. The act did not, however, contain any “one-in-five” requirement, nor did it even suggest the use of stretches of the interstate system as emergency landing strips. The one-out-of-five rule was not part of any later legislation either.

This myth could be countered without suggesting that this is such a crazy idea. Small, private airfields would not likely have the length for modern jets nor be able to stand the weight of larger aircraft, particularly bombers. Additionally, the federal government spent large sums of money on interstate highways; wouldn’t they have wanted to get more out of their outlay?

Another way to counter this myth would be to make a larger argument that yes, Americans considered driving so important that the government was willing to subsidize the construction of interstates. In other words, the highways are more about our love for and reliance on cars and trucks than a nefarious Eisenhowerian plan benefiting the military-industrial complex.

The Federal Highway Administration has an official myth-busting page. Here is their answer to two questions of whether interstates were built with defense purposes in mind:

President Eisenhower supported the Interstate System because he wanted a way of evacuating cities if the United States was attacked by an atomic bomb.

President Eisenhower’s support was based largely on civilian needs—support for economic development, improved highway safety, and congestion relief, as well as reduction of motor vehicle-related lawsuits.  He understood the military value of the Interstate System, as well as its use in evacuations, but they were only part of the reason for his support.

Defense was the primary reason for the Interstate System.

The primary justifications for the Interstate System were civilian in nature.  In the midst of the Cold War, the Department of Defense supported the Interstate System and Congress added the words “and Defense” to its official name in 1956 (“National System of Interstate and Defense Highways”).  However, the program was so popular for its civilian benefits that the legislation would have passed even if defense had not been a factor.

Interesting that the federal government hosts such a page…