(CNNMoney) -- New cars sold in the United States must now be outfitted with rearview cameras to try and reduce the number of deaths and injuries that happen when vehicles back over people.
The federal safety requirement took effect on Tuesday, about four years after it was first announced by the National Highway Traffic Safety Administration.
"NHTSA prioritizes safety on US roads, and yesterday we reached an important milestone," said NHTSA administrator Heidi King, in a statement on Wednesday. "This technology helps drivers see behind the vehicle, which we anticipate will help save lives and prevent injuries."
The rule applies to all new vehicles weighing fewer than 10,000 pounds, whether they're manufactured in the US or imported. Most models of cars, SUVs and trucks weigh less than 10,000 pounds.
Most new cars are already in compliance with the rule. According to the Insurance Institute for Highway Safety, 97% of 2018 models have rearview cameras, compared to 8% in 2006.