Among states that don't require formal driver training, the rate of teens who have not had driver's ed is even greater, although that doesn't mean teens are any less safe behind the wheel, researchers caution.

"This shouldn't be used as an alarm bell," said Jean Shope, a professor at the University of Michigan Transportation Research Institute, who was not involved in this study. "I don't think from what's written (in the study) that we can conclude that if someone didn't take it, they're a bad driver or they should've taken it. We just don't know."

Driver's ed typically involves 30 hours of classroom learning and six hours behind the wheel with an instructor. Schools sometimes offer the classes, and there are also privately run programs.

The original aim of driver's ed was to produce safer teenage drivers, as they are four times more likely overall to crash than older drivers.

Most studies have not shown that driver education programs actually result in fewer crashes, however.

There are some efforts now to update these programs nationwide to make them more effective at improving safety.

To get a handle on just how many teens go through formal training before getting a license, the research team surveyed more than 1,700 high school students from 34 states, 25 of which have a driver-education requirement.

In the journal Pediatrics, the authors report that the states without a requirement had lower rates of teens going through driver education, and certain groups of kids -- including blacks, Hispanics, boys and kids with low academic achievement -- had especially low numbers.

"We would like to see higher numbers in the states that don't have requirements, since more than one in three teens in these states still aren't getting drivers ed," said Allison Curry, the study's lead author and a researcher at the Center for Injury Research and Prevention at The Children's Hospital of Philadelphia.

In states in the Midwest with no mandate, for instance, only three out of 10 teen drivers had gone through formal training, compared to more than nine out of ten teens in Midwestern states with a driver's ed mandate.

"You can imagine in states that don't have driver education mandates, some jurisdictions may not offer school based driver education. So overall it might be less accessible in states without mandates," Curry told Reuters Health.

Among Hispanic students who lived in states without a requirement, just three out of 10 went through driver education, compared to eight out of 10 in states with a requirement.

A little more than half of boys, black students, kids who earned poor grades, and kids who went to schools in lower socioeconomic-status areas had had driver education in the no-requirement states, compared to more than eight in 10 members of those groups in the other states.

"I think some of the finding has to do with logistical and financial burden when there are no mandates," Curry told Reuters Health.

If states have fewer school-based programs, students have to seek out private programs, which can cost several hundred dollars.

"It's not that surprising that there's more driver education in situations where you might have a higher socioeconomic status," said Shope.

Curry said the findings for black and Hispanic students, males, and kids from poorer areas "is especially concerning...because these groups have been shown to have higher rates of risky driving behaviors and crashes."

But it's not clear that increasing the rates of driver education will lead to fewer crashes.

Shope said driver education is good way to help teens learn to maneuver a car and understand the rules of the road, but it doesn't necessarily make them safer.

"What we think makes a bigger difference is the supervised practice driving that a teen does, hopefully for many months, usually with a parent in the car," Shope told Reuters Health.

Curry said there's been an interest among researchers and policy makers to produce a more updated, national curriculum based on a better scientific understanding of how driver safety can be improved among teens.

The current "curriculum has largely remained unchanged since driver education was first introduced in the mid 1950s," Curry said.

The National Highway Traffic Safety Administration has provided recommendations to update states' driver education programs to incorporate practices based on research findings.

In a statement emailed to Reuters Health, NHTSA Administrator David Strickland said, "with teen drivers continuing to account for a disproportionate number of the fatal crashes on our roadways each year, NHTSA has made it a priority to work with our state safety partners to tackle this issue head on."

The NHTSA's new guidance encourages evidenced-based practices such as getting parents more involved in driver training and extending the time spent in the classroom and behind the wheel.

Curry said she's optimistic that, if they are implemented, the recommendations will improve driver education.

SOURCE: bit.ly/wnfZVX Pediatrics, February 13, 2012.

• A Permanent Economic Emergency