(Bloomberg) -- Hold the Champagne on celebrating a milestone in jobs for young adults in the U.S. -- and not just because many of them are below the legal drinking age.

While President Donald Trump proclaimed on Friday that youth unemployment was at a half-century low -- true, when looking at the jobless rate -- the actual number of Americans ages 16 to 24 who are working remains a few million below the peak in the late 1970s. One big reason: More are focusing on school full-time and aren’t bothering to look for jobs.

“Just announced, youth unemployment is at a 50 year low!” Trump tweeted following a Labor Department report Thursday saying that the youth unemployment rate of 9.2 percent was the lowest for a summer since 1966.

The lower unemployment rate, though, obscures huge changes in the labor force that make that statistic less meaningful today. With high-tech jobs requiring specialized skills, more young people are skipping summer and part-time work in favor of being full-time students.

The labor-force participation rate among Americans 16 to 24 years old was 55.5 percent in July -- 10 percentage points lower than in July 1999, which was near the end of the longest U.S. expansion on record. People who are in school and not actively looking for work are counted as not participating in the labor force.

Employment remains well below the level between the mid-1970s and 2001, said Gary Burtless, a senior fellow at the Brookings Institution in Washington and a former Labor Department economist. The declines are “traceable to increases in school and college attendance in the age group. Young adults attending school full-time are less likely to be employed, especially in full-time jobs.”

About 20.9 million young people had jobs in July, the most in 10 years, reflecting steady gains since the recession ended in 2009. Still, that’s actually fewer than the 22.2 million in July 1999 as well as the peak July level of 25.1 million in 1979.

Besides education, another factor is that “disadvantaged and African American young people also disengage due to the poor prospects they perceive in the labor market, and that continues to be the case,” said Harry Holzer, a public-policy professor at Georgetown University. “And those incarcerated or with criminal records often don’t even show up in our population numbers.”

While young people focusing on learning is a positive for the economy over the long term, some of the decline may be related to related to drug use that creates a lasting scar. Opioid use by American men may account for one-fifth of the decline in their participation in the U.S. labor force, according to a 2017 study by Princeton University economist Alan Krueger.

To contact the reporters on this story: Steve Matthews in Atlanta at smatthews@bloomberg.net;Alex Tanzi in Washington at atanzi@bloomberg.net

To contact the editors responsible for this story: Scott Lanman at slanman@bloomberg.net, Jeff Kearns

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