The number of teenage drivers or passengers who died in a traffic accident fell by 55 percent over the course of a recent decade, according to the Centers for Disease Control and Prevention. Meanwhile, the Connecticut Department of Motor Vehicles reports that the number of 16- and 17-year-old drivers killed in accidents in the state dropped by 64 percent in a similar period.

The CDC says that between 2004 and 2013, the number of teenage drivers involved in fatal accidents in the United States fell from 5,724 to 2,568. The organization says the decline is a result of factors such as graduated driver licensing laws, improved vehicle safety, and the trend of teenagers waiting longer to acquire a license.

The Connecticut DMV also credited graduated driver licensing laws for the reduction in fatalities. The organization says 2014 marked the first time in 12 years that no 16- or 17-year-old passengers were killed in a vehicle driven by another 16- or 17-year-old in the state.

CDC findings

To analyze driving behaviors, the CDC used data from the 2013 Youth Risk Behavior Survey, a voluntary and anonymous questionnaire. This information, collected from 42 states and 21 large urban school districts, was used to estimate the number of teenage drivers who had driven within the past 30 days.

A total of 76.3 of high school students who were at least 16 years old reported driving sometime in the 30 days before the survey. The likelihood of driving increased with age. While only 69.8 percent of 16-year-olds said they had driven within 30 days of the survey, this share increased to 78 percent of 17-year-olds and 84.2 percent of respondents who were 18 or older.

Location played a significant role in driving habits. Teenagers were least likely to drive in Hawaii, where 53.8 percent of respondents said they had driven a car or other vehicle in the 30 days before the survey. South Dakota had the highest share of teenage drivers at 90.2 percent. In Connecticut, 67.7 percent of respondents said they had driven a car recently.

Teenagers in the Midwest and Rocky Mountains states were more likely to have driven than teenagers in other regions. In the urban school districts, a median of 57.7 percent of teenagers reported driving in the past 30 days. This share ranged from 76 percent in Charlotte-Mecklenburg, North Carolina, to only 30.2 percent in San Francisco, California.

The CDC says the disparity among different regions is likely due to lower population density and fewer options for alternative transportation in the Midwest and Rocky Mountains. The organization says the lower shares of teenage drivers in urban areas may be related to family income, shorter travel distances, and the availability of transportation options such as public transit, walking, and bicycling.

The report also identified significant racial differences among teenage drivers. A total of 83.2 percent of white respondents said they had driven in the past 30 days, compared to 68.9 percent of Hispanic students and 67.6 percent of black students.

While the CDC says a decline in teenage license and driving coincided with the economic recession of the mid-2000s, rates have not increased in recent years. Reasons for not getting a license may include lack of access to a vehicle or avoiding the costs of owning and operating a vehicle.

The CDC says that such delays may affect a driver's ability if he or she gets a license when they are older. Graduated driver licensing programs implement certain requirements for teenage drivers, including a minimum number of hours of supervised driving and restrictions on passengers or nighttime driving, to allow the young driver to gain driving experience under relatively safe conditions. However, these programs rarely apply to novice drivers over the age of 18.

Researchers are currently looking into how a teenager's decision to wait until their 18th birthday to get a driver's license affects their driving ability and safety. The CDC says some researchers have advocated extending graduated driver licensing rules to new drivers between the ages of 18 and 20.

The report notes that there are several limitations to the conclusions of the study. These include the possibility of underreporting or overreporting of certain behaviors due to the voluntary nature of the survey, a lack of data from several states, and the concentration of the urban school districts in cities on the East Coast and West Coast.

DMV findings

The Connecticut Department of Motor Vehicles' conclusions were released in the 2014 Teen Safe Driving Report. In addition to its findings on teen driving habits and safety, the report includes the results of a study by the Connecticut Children's Medical Center on the effects of graduated driver licensing laws.

The number of deaths among 16- and 17-year-old drivers fell 64 percent between the 1999 to 2003 period—before the implementation of Connecticut's graduated driver licensing laws in 2004—and the 2011 to 2014 period. The graduated driver licensing laws were strengthened in 2008.

The death of a 17-year-old East Hartford driver marked the only 2014 fatality among 16- and 17-year-old Connecticut drivers, who are subject to the graduated driver licensing laws. There were no deaths of 16- or 17-year-old passengers in the state who were riding in a vehicle driven by a driver in the same age group.

Crashes with injuries were also on the decline in this age group, falling 13 percent in 2013 when compared to the two prior years.

"I applaud all the work done since the passage of tougher laws to save lives and we need to remain aware that even more work is needed every year to reach new teen drivers and the many people who influence them," said DMV Commissioner Andres Ayala, Jr.

Licensing among 16- and 17-year-old drivers has fallen significantly in recent years. While 29,903 licenses were issued to drivers in this age group between 2006 and 2008, the number fell to 25,439 between 2009 and 2014. The DMV says that several factors may be contributing to this decline, including economic considerations and changing attitudes among teenagers about getting a license.

Connecticut's graduated driver licensing laws only apply to 16- and 17-year-old drivers. These include restrictions on passengers, a curfew to prevent nighttime driving, and a ban on using any kind of cell phone or mobile device while driving.

The study by the Connecticut Children's Medical Center concluded that while teenage fatalities in the state have gone down in the state, half of the fatal crashes involving 16- or 17-year-old drivers occurred because the driver was in violation of a graduated driver licensing law. In most categories, violations had increased slightly when compared to previous year. Speeding violations among young drivers had the most significant increase, going from 846 in 2013 to 1,053 in 2014.

Researchers also noted some shortcomings among parental understanding of the laws. Forty percent had insufficient knowledge on the nighttime curfew and as many as 24 percent did not answer correctly when asked about passenger restrictions.

"We have made significant progress with GDL laws in Connecticut, but we need to get parents more engaged to make certain their teens obey the GDL laws," said Dr. Brendan Campbell, a trauma surgeon and director of the Pediatric Trauma Program at Connecticut Children's Medical Center.