College graduation season is in full bloom, and this year American institutions will confer about 1.8 million bachelor's degrees. As in the past, many of the best and brightest have, or will land, jobs requiring knowledge, skills and critical thinking -- and will be paid good salaries. But increasingly, today’s college graduates face an uncertain future, and many will end up taking jobs historically done by those with high school diplomas or even less -- construction workers, taxi drivers, restaurant wait staff, janitors. More than 1 million college graduates are retail salespeople -- about twice the number of active-duty U.S. Army personnel.

Is this largely a temporary phenomenon, a function of sluggish job growth in recent years? The financial crisis, the recession and mediocre recent economic growth have certainly aggravated things. But this is a long-term problem: There are simply more college graduates than jobs requiring college degrees.

The problem will probably get much worse in the next decade. The Bureau of Labor Statistics issues 10-year projections of job growth by occupation, including estimates of the “typical education needed for entry.” The most recent projections cover 2012 to 2022. During that period, there will be an estimated net increase of 15,628,000 jobs, but only about 27 percent of them (4,230,500) will require a bachelor’s degree or more. More than twice as many of those jobs (8,789,200) are estimated to require no postsecondary education at all. In the 2001-11 decade, about 15 million people received bachelor’s degrees, and the number of college graduates per year has been rising.

To be sure, people retiring, currently unemployed college graduates taking jobs and immigration of college graduates will also impact the number of workers with degrees. But my best guess, based on historical trends, is that the number of college graduates will increase by, conservatively, 17 million over the decade -- suggesting that in 2022 only about a quarter of new college graduates will be in the new jobs requiring university training (although some others will also replace existing workers who retire or quit).

None of the 10 occupations with the largest projected job growth require bachelor’s degrees, and only one (registered nurses) requires a two-year associate's degree. Six of the top 10 jobs require less than a high school diploma (personal care aides, retail salespersons, home health aides, food preparation and serving, janitors and cleaners, and construction laborers). Among the 30 jobs projected to have the greatest growth, only five require at least a bachelor’s degree (general and operations managers, elementary school teachers, accountants and auditors, software developers, and management analysts).

As employers see an influx of college-degree holders, they are raising job educational requirements simply to narrow the applicant pool, assuming on average college graduates are smarter and more dependable than those with high school diplomas. Thus, while the BLS says registered nurses or secretaries and administrative assistants need less than a bachelor’s degree, employers of those workers are increasingly demanding degrees -- because they can -- causing large-scale credential inflation and increasing unemployment among the lesser educated.

This underemployment problem is not evenly distributed across higher education. Lecturing at Williams College recently, I was struck by how many seniors were getting dream job offers from Silicon Valley or Wall Street. Employers know that a large portion of the best students attend these highly selective schools. The picture is radically different at the relatively nonselective public universities or relatively obscure liberal arts colleges with small endowments.

Solving the problem will be very difficult so long as politicians find it expedient to dole out aid and cheap loans to students who don’t belong in college at all, and whose prospects for both academic and vocational success are small. Of course, the BLS might be wrong. And markets work. As the word spreads that college degrees do not guarantee vocational success, enrollments may fall. If the economy gets out of its recent funk, job creation might become more robust.

Indeed, there are recent, promising signs that publicity about the unemployment problem is leading some to ignore government financial enticements and look to more appropriate nondegree postsecondary training. But as the federal student-loan default rate reaches crisis levels, what we really need to do is radically revise our dysfunctional, inefficient system of federal financing of higher education. Until then, we will have a lot of graduates with low paying jobs, big debts and unfulfilled expectations.

To contact the writer of this article: Richard Vedder at vedder@ohio.edu.

To contact the editor responsible for this article: Zara Kessler at zkessler@bloomberg.net.