No one knows exactly how rumors get started. Sometimes they’re quickly debunked and go away, but other times they persist – like the idea that United States highways were intentionally designed to function as emergency runways.

We’re not sure where it actually came from, but the idea seems to stem from legislation that was passed in the 1940s. There have always been arguments on both sides, like the common sense need for emergency runways and the fact that there are many highways too hilly or small to work for military aircraft.

Not to mention the fact that, at any given day and time, people are driving on said highways.

There are purported answers, such as that the whole road isn’t necessary, because every 1 mile out of 5 is all that’s required to account for turns, elevation changes, and population.

The legislation actually exists, too – the Defense of Highway Act of 1941, the Federal-Aid Highway Act of 1944, and the Federal-Aid Highway Act of 1956 – though none of them contain any language about emergency runways or the 1-in-5-mile rule, either.

The Defense Highway Act provided flight strips near highways and the Federal-Aid Highway Act came comes to adding a flight strip program but ultimately did not.

In reality, the strategy really isn’t practical since there’s no way local law enforcement would have time to close off a highway in time if the plane was having a true emergency – one that wouldn’t allow them to divert to the nearest actual runway.

Plans for emergency landings instead include municipal and private airports, military bases, and other small and little-known runways that could serve in tight spots.

It sounds like, while this theory might have made sense when the highways were being built, the fact is that now there are runways everywhere.

So try not to worry about being crushed by a jet while you’re driving – the guy next to you texting on his phone is a far bigger concern.