In four years, when you buy a new car or truck it’ll have a rearview camera as a standard feature. That’s because it’ll have to under a new rule just issued by the U.S. Department of Transportation’s National Highway Traffic Safety Administration.

The NHTSA just issued its final rule after delaying it the first time around — the requirement was supposed to go into effect by 2014 but was pushed back in 2012. The agency says it took its time to make sure the rule was flexible enough, pointing out that many automakers have already started installing systems on their own.

The rule applies for all vehicles under 10,000 pounds, including buses and trucks, that are made on or after May 1, 2018. All those vehicles will have to include technology that expands the field of view to allow drivers to see behind the vehicle in a 10-foot by 20-foot swath.

At the heart of the rule is the fact that many drivers end up backing over things they shouldn’t, putting themselves and anyone standing behind a car in potential danger. The NHTSA says there are an average of 210 fatalities and 15,000 injuries per year due to backover crashes.

“Safety is our highest priority, and we are committed to protecting the most vulnerable victims of backover accidents — our children and seniors,” said U.S. Transportation Secretary Anthony Foxx. “As a father, I can only imagine how heart wrenching these types of accidents can be for families, but we hope that today’s rule will serve as a significant step toward reducing these tragic accidents.”

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