CODY, Wyo. — Barely five people per square mile live on the high, wind-raked ground of Wyoming; the entire state is a small town with long streets, as they say. The open space means room to roam and a sense of frontier freedom.

It also means that on any given night, an unusually high percentage of young people here are drinking alcohol until they vomit, pass out or do something that lands them in jail or nearly gets them killed.

"Had a kid, drunk, flipped his car going 80 miles an hour and that killed him; and another kid, drunk, smashed his boat up against the rock just a couple months ago, killing two; and then there was this beating after a kegger — they clubbed this kid to death," said Scott Steward, the sheriff here in Park County, recounting casualties that followed long nights of hard drinking by high school students.

A federal government survey recently confirmed what residents of Wyoming, Montana and the Dakotas already knew: People in a handful of northern tier states drink to excess, at very early ages, well above the national average.

The survey, conducted over three years by the federal Substance Abuse and Mental Health Services Administration, said south-central Wyoming led the nation with the highest rate of alcohol abuse by people age 12 and older. In Albany and Carbon counties, more than 30 percent of people under age 20 binge drink — 50 percent above the national average.

In examining behavior in 340 regions of the country, the survey found that seven of the top 10 areas for underage binge drinking — defined as five or more drinks at a time — were in Wyoming, Montana and North and South Dakota.

At the other end of the scale, some of the lowest areas for underage binge drinking were in the nation's most densely packed cities — parts of Washington, D.C., Detroit and Los Angeles. An earlier federal study found that rural youths ages 12 and 13 were twice as likely as urban youths to abuse alcohol.

With methamphetamine ravaging small towns, Wyoming and other rural states have also been fighting a persistent drug problem.

And while it may be a mystery to some why the least-populated part of the country leads the nation in the percentage of young people drinking to excess, it is not so in Wyoming or neighboring Montana. Teenagers, police officers and counselors offer the same reason: the boredom of the big empty.

"After living in the city, it's obvious to me that kids just get bored here," said Karen Grimm, the mother of a freshman at Cody High School, who moved here from Seattle 10 years ago. "There is this feeling of isolation, especially in the wintertime."