(Bloomberg Business) -- Teen unemployment remains sky-high. Itwas 17.1 percent in April. The Bureau of Labor Statistics willrelease the May numbers on Friday, and they probably won't be muchbetter.

But today's teens have something very bigon their side: There aren't very many of them. So as they entertheir prime working years, and boomers keep retiring, they will bein high demand. That's according to Gad Levanon, the managingdirector for the economic outlook and labor markets at theConference Board in New York.

Teens belong to Generation Z, the small cohort coming alongbehind the large Millennial generation. Gen Z is justbeginning to reach working age. Pew Research uses 1997 as theend of the Millennial generation, while acknowledging that "nochronological end point has been set for this group." If the oldestGen Zers were born in 1998, they're turning 17 this year.

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Over the next couple of decades, the smallness of Generation Zwill lead to tightness in the labor market, argues Levanon. Hebases this on a metric called the 17-to-64 gap. It's the idea thatthe labor force grows when the number of 17-year- olds (who areabout to turn 18 and enter prime working age) exceeds the number of64-year-olds (who are about to turn 65 and exit the prime workingage cohort).

As recently as 2000 there were still 2 million more 17-year-olds than 64-year-olds. The gap shrank to around 700,000 in2011 as the oldest boomers hit age 65 and it will shrink to almostnothing by the mid-2020's, Levanon says, citing Census Bureauprojections.

"The contribution to population growth of this gap is about0.4 [percentage point] now, and it will gradually shrinkto almost zero in the next decade," Levanon and his colleagueMichael Paterra wrote in a blog post last month.

The growth in America's working-age population in the 2020s willbe sustained primarily by immigration, Levanon and Paterra write.And it won't be much: a measly 0.2 percent or so in 2025, downfrom around 1.3 percent in 2000.

These numbers may sound surprising, but they aren't exactlypulled from thin air. They're based on Census Bureauprojections. In a new report, the Census Bureau projects thatthe working-age share of the population will fall from 62 percentin 2014 to 58 percent in 2030, then level off.

Of course, this is only the supply side of the equation. Whetherthe dearth of Gen Zers results in labor shortages depends onthe demand side--namely, how much labor the economy will need incoming years. Some economists argue that computerization,robots, and foreign outsourcing will kill demand for workers.

Others say that those forces will simply free up Americanworkers for jobs that can't yet be imagined yet, as happened duringthe transition from farm to factory and later from factory to theservice economy.

If labor shortages do develop, one force that could amelioratethe problem is the rise of what a new report from McKinsey GlobalInstitute calls "online talent platforms"-- websites like LinkedIn,Glassdoor, and Monster that match people with traditional jobs,plus online marketplaces like TaskRabbit and Uber that connectpeople to contingent or freelance work. Worldwide, "Up to 540million individuals could benefit from online talent platforms by2025," the institute says.

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