WASHINGTON -- The U.S. Department of Transportation (DOT) on Aug. 29 marked its annual enforcement crackdown and the launch of a nationwide, multi-year advertising campaign aimed at getting drunk drivers off the road: "Drive Sober or Get Pulled Over."

With new research showing fatal crashes involving drunk drivers occur most frequently between the hours of midnight and 3 a.m. -- when drunk-driving crashes claim a life every 23 minutes -- the efforts are particularly focused on nighttime enforcement.

"While we have made great strides in reducing drunk driving over the years, tragically, drunk driving remains one of the leading causes of death and injury on America's roads," said U.S. Transportation Secretary Ray LaHood. "Through our new national advertising campaign and stepped up law enforcement actions, we're sending a powerful message to the American driving public -- Drive Sober or Get Pulled Over."

A new analysis by DOT's National Highway Traffic Safety Administration (NHTSA) shows the highest risk of being involved in a fatal crash with a drunk driver occurs between the hours of midnight and 3 a.m. Two-thirds of the fatal crashes during these pre-dawn hours involve drunk drivers. Other key findings include:

One in four of the nearly 11,000 people killed in a crash involving a drunk driver in 2009 died between the hours of midnight and 3 a.m.

One in three drivers 21 to 24 years old involved in fatal crashes were alcohol-impaired. Drivers 25 to 34 years old were the second most likely to be involved in these types of crashes.

The next worst times of day with particularly high percentages of alcohol-impaired crashes were 9 p.m. to midnight and 3 a.m. to 6 a.m.

New advertising released by DOT this month and running in major media markets across the country features "invisible" law enforcement officers observing alcohol-impaired individuals unseen before apprehending them when they attempt to drive their vehicles. Coinciding with the advertising push, states are engaged in stepped-up enforcement efforts in communities nationwide. The ad theme and slogan will comprise DOT's core drunk driving message for 2011–2016.

"Law enforcement officers across the country are out in force, cracking down on anyone who breaks the law and drives drunk," said NHTSA Administrator David Strickland. 

Targeting drivers in the final weeks of summer from Aug. 19 through the Labor Day holiday weekend, the annual crackdown is focused on reducing the tragic toll caused by impaired drivers every year. The efforts involve more than 10,000 police departments and other law enforcement agencies across the nation, who will be redoubling their efforts. during this high-risk travel period.

NHTSA's study evaluating alcohol fatalities by time of day is available here.