Nearly eight in 10 Americans have admitted expressing anger, aggression or road rage at least once in the last year.
Routine bad behaviour included following too closely, yelling at another driver, cutting them off or making angry gestures, according to a survey by the AAA Foundation for Traffic Safety.
But an estimated eight million drivers engaged in much more extreme acts, including bumping or ramming a vehicle on purpose or getting out of their cars to confront another driver, the foundation said.
The most aggressive and aggrieved drivers were young men aged 19 to 39. Men were three times more likely than women to have got out of a car to confront another driver or rammed another vehicle deliberately.
"Far too many drivers are losing themselves in the heat of the moment and lashing out in ways that could turn deadly," Jurek Grabowski, the foundation's research director, said.
The foundation's findings are based on a nationally-representative online survey of 2,705 licensed drivers who had driven at least once in the previous 30 days. The survey was conducted in 2014, but its results are just now being released.
Research indicates aggressive driving contributes substantially to fatal crashes and it appears to be increasing, the foundation said in a report based on the survey.
Nearly nine in 10 drivers saw aggressive driving as "a serious threat to their personal safety", the foundation said. And more than half of drivers perceived road rage as a bigger problem than in a survey three years earlier.
The most common behaviour, reported by about half of all drivers, was purposely tailgating another vehicle. That translates to about 104 million drivers when spread over the national population of motorists.
Nearly half of drivers reported yelling at another driver and hooting "to show annoyance or anger". About a third of drivers indicated they had made angry gestures at another driver.
Gesturing, honking and yelling at other drivers were significantly more prevalent in America's Northeast. Northeastern drivers were 30% more likely to say they had made an angry gesture at another motorist. Other types of aggressive behavior did not vary much by region.
About one in four drivers said they had purposely tried to block another from changing lanes and nearly 12% reported they had cut off another vehicle deliberately.
Drivers who reported other unsafe behaviour like speeding and jumping red lights were also more likely to show aggression. Drivers who reported speeding on a freeway in the previous month were also four times more likely to have cut off another vehicle in traffic.
The National Highway Traffic Safety Administration estimates that about two-thirds of crash deaths involve aggressive driving. The agency recently reported that traffic deaths surged last year to 35,200 as drivers racked up more miles behind the wheel than ever before.
Jake Nelson, the AAA's director of traffic safety advocacy, urged motorists to "maintain a cool head and focus on reaching your destination safely".
"Don't risk escalating a frustrating situation, because you never know what the other driver might do," he said.