The report from the Substance Abuse and Mental Health Services Administration was based on 2002 and 2003 figures. The 2004 total would amount to 21 percent of U.S. youth in that age group.

When the two years of data are looked at separately, driving under the influence was reported by 22 percent of 16- to 20-year-olds in 2002 and 20 percent in 2003.

"This is a major public health issue," SAMHSA Administrator Charles Curie said. "As we approach New Year's Eve celebrations, adults have to be cognizant that more than one in five youths are driving after using illicit drugs or illegally consuming alcohol, or both. Motor vehicle crashes are the leading cause of death among young persons 16-20."

The SAMHSA data show approximately 25 percent of the young people in the Midwest reported driving under the influence. This compares to approximately 20 percent who lived in the South and 19 percent of those who lived in the Northeast or the West.