Answer: Right Turn On Red

Although U.S. drivers take turning right on red lights for granted these days (outside of the few areas where it remains restricted), historically, right-turn-on-red wasn’t widely adopted outside of sparsely populated areas in western states.

All that changed when the gasoline shortages of the 1970s left the U.S. government reaching for any solution that would increase fuel efficiency and cut down on consumption. Federal Highway Administration sponsored studies revealed that allowing right-turn-on-red when traffic was clear reduced the waiting time by 9 to 30 percent based on traffic conditions and, as such, actually made a pretty significant dent in the amount of time drivers spent idling.

By early 1980, all fifty U.S. states had adopted right-turn-on-red regulations and what was a driving curiosity forty years ago is commonplace today.