America is a nation of aggravated drivers, and they are growing more aggravated by the year, according to a new survey.

Bad roads, traffic delays and personal worries all play a part in increasing frusrtration, but other drivers may be the biggest factor.

Discussion: Do Drivers Drive You Crazy?

Forty percent of drivers describe driving as "aggravating" and "more aggravating than two years ago," according to the poll conducted for Drive for Life, a driver safety awareness initiative.

Both men and women agreed other drivers are the prime source of their aggravation, but the behaviors that set them off divide the genders. Men complained of drivers who talk on cell phones and drive while distracted, while women are more bothered by aggressive behaviors like speeding and tailgating.

One in four men admitted to driving angry, compared to one in five women.

All that anger takes a toll: 18 percent of Americans polled said aggressive drivers pose the biggest threat on the road, second only to drunk drivers. Another finding was that 37 percent of teenage drivers admit to driving while emotionally upset -- more than twice the rate for older people.

The all-around angriest, most aggravated, most dangerous age group on the road was those in their early 20s, who were most likely to describe themselves as fast and aggressive drivers, least likely to wear a seat belt or require a passenger to wear one, and most likely to have received a traffic ticket within the past two years.

A poll of 1,100 licensed drivers was done to find the figures. Drive for Life is sponsored by AAA, Volvo Cars of North America, Partners for Highway Safety, the National Association of Police Organizations and the National Sheriffs' Association.