The percentage of American high school students who drink and drive has dropped by more than half in two decades, in part because of tougher laws against driving under the influence of alcohol, federal health officials said on Tuesday.
In 2011, 10.3 percent of high school students 16 and older reported drinking and driving in the previous 30 days, compared with 22.3 percent in 1991, according to a new study by the Centers for Disease Control and Prevention.
The agency credited the nearly 54 percent decline to stricter laws against drunken driving and restrictions on teenagers' driving privileges, like limits on the hours they may legally drive at night.
"We've seen really good progress," Dr. Thomas R. Frieden, the director of the centers, told reporters. "We're moving in the right direction, but we need to keep up the momentum."
Despite the decrease, nearly a million high school students consumed alcohol before driving last year, the report showed.
Drinking and driving among teenagers is a factor in more than 800 deaths annually, and car crashes remain the leading cause of death among people aged 16 to 19, the centers said.
For the report, the agency analyzed risk behavior data collected from thousands of high school students through national surveys and from 41 states.
In 2011, the percentage of students who reported drinking and driving in the previous 30 days ranged from a low of 4.6 percent in Utah to a high of 14.5 percent in North Dakota.
Male students 18 and older were the most likely to drink and drive, and 16-year-old female students were the least likely, it said. Eighty-five percent of high school students who reported drinking and driving in the prior month also admitted binge drinking, defined as having five or more drinks during a short time period.
The centers said another factor in the decline of teenage drinking and driving was that high school students were driving less, possibly because of higher gasoline prices and the slowdown in the economy.
From 2000 to 2010, the percentage of high school seniors who did not drive during an average week jumped to 22 percent from 15 percent, the health agency said.
Dr. Frieden said parents were vital in ensuring that rates of teen drinking and driving continue to decrease.
"Children see how their parents drive from a young age and model that behavior," he said. "Parents are a key part of the equation here."