WASHINGTON -- The law that established 21 as the national drinking age turns 21 tomorrow, but the birthday celebrations will be muted.

Federal officials estimate that the law signed on July 17, 1984, by then-President Ronald Reagan has saved the lives of more than 20,000 young people who otherwise would have died in alcohol-related traffic accidents, but underage drinking remains a serious national problem.

Nearly a third of youths aged 12 to 20 -- 11 million kids -- drink alcohol, according to a 2004 study by the federal Substances Abuse and Mental Health Services Administration, and underage drinkers consume between 12 and 20 percent of alcoholic beverages in the United States.

"The National Academy of Sciences called the problem of underage drinking 'endemic,' " said David Jernigan, research director for the Center on Alcohol Marketing and Youth at Georgetown University. "This is the nation's No. 1 drug problem -- 7,000 kids under the age of 16 start drinking every day. ... The problem isn't going to go away without significant new intervention strategies."

Yet Jernigan, like other public safety advocates, said it's important to acknowledge the significance of the law that established the 21 drinking age. "It was a huge step forward," he said. "What happened is that we got big gains in reducing underage drinking because of '21' through the early 1990s."

Glynn Birch, new national president of Mothers Against Drunk Driving (and the first father to hold that position), said that "because of the 21 law, underage drinking deaths have been cut from 8,000 annually in the 1980s to 6,000 per year today."

In the past decade, however, efforts to further reduce underage drinking have stalled.

"Some indicators are slightly down, some are slightly up -- looking at the whole picture is how we conclude that little if any progress is being made, despite enormous efforts at the local and state levels, in terms of tightened enforcement, educational programs, etc., etc.," Jernigan said.

For example, in 1984, more than half of fatal crashes caused by drivers aged 15-20 were alcohol-related. By 1994, that figure had dropped to 22 percent, but it rose to 31 percent in 2003, federal statistics show. Underage drinking by girls is increasing in some age groups as well, according to public safety advocates.

"We are also seeing an increasing number of those who drink to the point that they are sick," said Patricia Harmon, executive director of Ohio Parents for Drug-Free Youth. "They are binge drinking ... and set out to get into an altered state, to -- as they put it -- 'get wasted.' "

In Pennsylvania, binge drinking is more prevalent among 10 th- and 12 th-graders than use of tobacco, marijuana or other illicit drugs, according to the 2003 Pennsylvania Youth Survey, the most recent available.

Binge drinking is a particular challenge for college administrators, and some believe that they could better tackle the problem if the drinking age were lowered to 18. Last fall, former Middlebury College President John McCardell advocated the lower age in a New York Times column, arguing that "colleges should be given the chance to educate students, who in all other respects are adults, in the appropriate use of alcohol."

Opponents cite recent research which indicates that the brain continues to develop until age 21, and that young brains can be irreversibly damaged by alcohol. They also point to studies showing that children who drink alcohol are more likely to abuse alcohol later in life.

"The research shows the devastating effect that alcohol has on adolescents, in terms of the damage to memory and judgment and the things that teenagers struggle with anyway," Harmon said.

In an effort to combat underage drinking, a bipartisan coalition of U.S. House and Senate members has introduced a bill called "Sober Truth on Preventing Underage Drinking," or STOP. Built on the recommendations of a 2003 National Academy of Sciences report, the measure would earmark $19 million annually to fund a high-level task force to coordinate federal programs and finance a national media campaign, research and new state and local programs.

"This bill will go a long way to expand and coordinate our nation's fight against underage drinking," said Sen. Mike DeWine, R-Ohio, who has co-sponsored the Senate measure with Sen. Chris Dodd, D-Conn. "Looking at recent studies, we know this problem is not going to go away by itself."

While the alcohol industry supports programs designed to reduce underage drinking, industry officials oppose the STOP bill, saying it would duplicate current programs. STOP supporters say federal efforts don't yet go far enough .

Supporters of raising the drinking age to 21 faced a similarly difficult political situation in the early 1980s.

During Prohibition, most states had set 21 as the minimum drinking age, but a campaign to lower the legal age to 18 began in 1970 -- the same year that Congress lowered the voting age to 18, mainly on the argument that young people old enough to get drafted for military service in Vietnam ought to have a vote in national policy and otherwise be treated as adults.

Twenty-nine states lowered their drinking ages to 18 between 1970 and 1975, but many soon witnessed an increase in alcohol-related traffic accidents. A number of states then began raising the legal age to 21 again, but others did not -- creating what Mothers Against Drunk Driving called "a checkerboard of state laws."

MADD took the fight to Washington, D.C., where Reagan established a commission on drunken driving that eventually recommended denying federal highway funds to states that refused to raise the legal drinking age to 21.

Despite his state's-rights philosophy, Reagan agreed to push the recommendation after a major lobbying campaign by MADD and a bipartisan coalition of lawmakers. Since Reagan signed the measure into law, it has saved an estimated 1,000 lives per year.

The law has become widely accepted. A new ABC News/Washington Post survey found that 75 percent of Americans consider underage drinking a serious problem in their communities. Eight of 10 polled said they would oppose efforts to lower the legal drinking age to 18.

Congress strengthened the law in 1995 by requiring states to approve "Zero Tolerance" laws to deter underage drinkers from driving. But MADD and others, including alcohol industry organizations like the Beer Institute, want to see better enforcement of the minimum-21 law. MADD plans to conduct compliance checks in 21 different cities this weekend to see how well it is being enforced.

Meanwhile, states have established a number of programs to discourage underage drinking, many aimed at parents. "What we are trying to do is change the environment in which people think that underage drinking is a right of passage," said Pennsylvania Liquor Control Board spokeswoman Molly McGowan. "That's why, in our media campaign, 'Don't Let Minors Drink,' we focus on parents and other adults." The program includes a Web site, dontletminorsdrink.com, which includes tips for parents.