FORTUNE — “Manufacturing has an image problem,” says Paul Gerbino, head of industrial-supply trade publishers ThomasNet News. “People think of it as dirty, dark, and low-paying.” That stereotype is one reason why companies that make tangible products are struggling to find candidates for about 237,000 job openings. To put that figure in perspective, it’s 89,000 more than the entire U.S. economy created in September.

The shortage isn’t new — demand for factory workers has been rising sharply every year since 2005 — but it’s poised to get a whole lot worse.

It all comes down to demographics. Consider: Almost 80% of the current manufacturing workforce is between the ages of 45 and 65, says a new report from ThomasNet.com. One-third are between 55 and 64 years old and starting to look toward retirement. Yet more than three-quarters of the manufacturers in the study said that fewer than 25% of their employees are under age 30, and most don’t see that changing anytime soon.  Read more