It’s easy to take for granted the 3.5 million American truck drivers who spend days and weeks at a time on the road, delivering goods such as food and clothing to our stores and other destinations nationwide.

The trucking industry is the lifeblood of the U.S. economy — and now a shortage of drivers is sharpening the focus on this critical industry as it struggles to fill thousands of job openings.

So what’s driving the trucker shortage?

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“First, our economy is strong, which is generating demand for freight transportation services,” Sean McNally, vice president for public affairs at the American Trucking Associations (ATA), in Arlington, Virginia, told LifeZette in an interview.

“Roughly 70 percent of all U.S. freight tonnage is moved by truck, and 100 percent of consumer goods like food, clothing, and fuel are carried to stores by trucks.”

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“This increase in demand, coupled with an aging work force [along with] competition from other vocations and some regulatory constraints, has left the industry short more than 50,000 drivers right now,” he added. (The average truck driver is 49 years old; the average American worker is 42.)

Things could get tougher for the trucking industry if current economic conditions continue. The truck driver shortage could grow to 174,000 by 2026, McNally said.

“It is important to note that fleets are not wanting for applicants, but because of the skilled nature of the job, they often struggle to find qualified applicants to fill driving jobs,” he said. “Truck drivers must have clean driving records and not have certain criminal convictions. They must also have professional training and licensing.”

Illinois-based truck-driving school 160 Driving Academy is stepping up to fill the void. Established in 2012, the company reaches out to businesses that need drivers — and pays the full tuition for prospective employees.

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In a short span of time, the academy has expanded to more than 32 locations across the Midwest; it employs 110 instructors. “We’re training them for companies, so when they get out of here, they have a job waiting for them,” Lowell Newbold, a lead instructor for the company, recently told Fox Business.

The average commercial truck driver makes $54,000 a year, according to the driving school’s website. Upon graduation from 160 Driving Academy, drivers are guaranteed a job that pays at least $40,000. Additional endorsements could yield drivers more than $100,000 a year.

“We believe — and there are bills currently being considered by Congress — that with additional training and supervision, we could have younger people become drivers safely.”

Perhaps filling the vacancies within the trucking industry will also require something of a paradigm shift, along with an emphasis on a promising future.

“There are efforts to recruit many types of people — college grads, women, minorities,” said McNally. “But generally speaking, being a truck driver is a path to a middle-class lifestyle without the ‘debt burden’ of a four-year college degree. Individuals can receive professional training in a few weeks or months and be on their way to a challenging but rewarding career.”

63,000 open truck-driver jobs in the U.S., The business that is trying to stop the trucker shortage: @JeffFlock with the report. https://t.co/zuNZYQaS6m — Neil Cavuto (@TeamCavuto) July 1, 2018

Rising wages could also attract more drivers to the trucking industry.

“For drivers who work in the national, irregular truckload sector [one of the largest segments of trucking and the one most affected by the shortage], the average salary has risen $7,000 since 2013,” said McNally. “In addition, numerous fleets are offering thousands of dollars in bonuses to recruit and retain drivers.”

He added, “ATA is working with Congress and the [Trump] administration on a number of initiatives to make it easier for people to take jobs in trucking. One of these efforts focuses on an apprenticeship-style program to lower the minimum age for commercial drivers from 21 to 18 years old.”

Appreciate the @washingtonpost for mentioning my bill, the DRIVE Safe Act, as one of the ways to address the driver shortage in the trucking industry ↓ https://t.co/7MjAWs2CuX — Rep. Duncan Hunter (@Rep_Hunter) July 3, 2018

“Right now,” McNally added, “to move goods across state lines, a person must have a CDL [commercial driver’s license] and be 21 years old or older. We believe — and there are bills currently being considered by Congress — that with additional training and supervision, we could have younger people become drivers safely.”

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Businesses right now are already feeling the pinch of higher transport costs.

“These could eventually be passed on to consumers, and if the shortage worsens, businesses could find it even more difficult to find carriers with trucks available to move their goods, potentially disrupting the supply chain and hurting the availability of goods at the store,” noted McNally.

The next time any of us reads the words, “free shipping,” we must know there are many costs involved — not the least of which is manpower.

Elizabeth Economou is a former CNBC staff writer and adjunct professor. Follow her on Twitter.