The world was running out of cassette tape. Now it’s being made in Springfield.

A sprawling factory on Water Street in downtown Springfield will soon be the only place in the country, maybe even the world, to make the tape that goes inside audiocassettes.

Yes, people still use those.

Lots of people. National Audio Company's factory makes more than 10 million cassettes per year.

In recent years, a worldwide shortage of tape showed few signs of relief. For a long time, National Audio muddled through by purchasing stocks of tape from other manufacturers.

Those companies were getting out of the tape-making game, said National Audio president and co-owner Steve Stepp.

"Nobody has made audiocassette tape in this country since about 1983 or 1984,” Stepp told the News-Leader in early December.

By December 2016, it was clear that the legacy supply of tape was finally drying up, Stepp said.

Thus, more than five decades after audiocassettes were invented by a Dutch engineer, a U.S.-based company decided to make tape again.

National Audio is set to begin production this month, having rescued a 62-foot tape-coating line weighing 20 tons from obscurity. Its former owner had converted it into a machine for making credit-card strips.

Soon, the tape coater will be back to its original purpose, after many months of reassembly and testing.

It will crank out 20,000 feet of tape per minute.

The tape is made of paper-thin polyurethane coated with a slurry made of ferric oxide and carbon black.

Once the polyurethane is coated and dried, it's sliced into slender bands so it can be spooled inside a cassette shell, or C-zeros as they're known in the trade. National Audio Company buys C-zeros in 30 colors from a family-owned company based in Italy.

The entire process — tape-making, cassette assembly, recording, labeling and shipping — happens under National Audio Company's roof.

It’s an old building with two sections. The five-story wing dates to 1882. It even has a working elevator from 1926 that Stepp, a history buff whose office is filled with vintage artifacts, calls "the modernization" of the structure. The nine-story side was built in 1936.

In 2018, the factory loads a minimum of 44 million feet of tape into cassettes each day.

National Audio used to get those millions of feet from a Chinese tape manufacturer. "It wasn't that great a product," Stepp said, not as good as tape that used to come from U.S. and South Korean companies.

National Audio's tape will be better-quality tape, Stepp said.

He added that cassettes are holding their own against downloadable and streaming music.

“It’s just all over,” he said. “I wouldn’t have any idea of the total market.”

Stepp rattled off a list of today’s key cassette markets, many of them locations where smartphones and MP3 players are commonplace: the Western Hemisphere, Europe, Japan, Indonesia.

So Stepp bought up the equipment needed to make tape and hired a trio of retired technicians and engineers to repair and upgrade it. They set up a mini-machine shop partitioned from the rest of the factory.

Their task was not a quick one: Bob Coverton, an engineer with experience working on high-speed tape duplicators in the '70s, likened it to working with "mismatched Lego kits."

Monte Chaney, a former KYTV broadcast engineer, noted that one component of the line contained food-grade pipe that got clogged with plastic after its previous owner stopped using it. "They just turned it off and let the plastic set up," he said.

"You might as well say we’re the MacGuyver team," quipped Ray Massey, the team's mechanic. "I’ve even got some bubble gum in my toolbox.”

Not far from the engineers' lair, a series of stark white rooms on the upper floors of the factory now contain the tape assembly line.

The machinery is more than 30 years old, decked out with dials and control switches that would fit in on the set of "Star Trek."

In one room, mixers allow for testing out various combinations of ferric oxide slurries. The slurry resembles chocolate pudding. Consistency is key.

"We don’t want thick and thin batches," Stepp explained.

Stepp calls the mixers "the world's biggest Kitchen-Aid." The largest one is a bit smaller than the mixer Askinosie Chocolate uses to grind cocoa nibs on Commercial Street.

A few steps away from the slurry mixers is the tape coater. It applies a microscopically thin layer of slurry to 13,000-foot sheets of polyurethane. Powerful magnets orient the iron oxide to create a recording medium.

After coating, the tape sheets pass through 48 feet of ovens, floating on 200-degree air that's been filtered down to 1 micron.

Filtering is critical, Stepp said. If particles get into the tape coating, the final sound quality is ruined.

Next, chrome rollers crush and polish the tape with about 15 pounds per square inch of pressure, giving the medium its characteristic glossy brown color.

In a third room, windows overlook the chunky concrete mounds of Founders Park, across the street. They shed light on machines that slice and spool the polyurethane lengthwise, from 6.5-inch sheets into 1/8-inch strips.

This fall, Stepp went public with his plans to get all this equipment up and running. The news brought reporters from the Wall Street Journal to town.

The Journal is not the first high-profile news outlet to turn its attention to National Audio Company.

For many years, its last-man-standing role has brought it coverage from Time, Bloomberg, the Washington Post, NBC Nightly News, Rolling Stone, Ars Technica, Fox Business and CNN, among others.

Frequently, journalists marvel at the strange fate of an aging medium in an era of constantly changing media formats.

Audiocassettes are six years older than National Audio Company, founded in 1969 by Stepp and his dad.

Since then, up to 100 billion tapes have been sold, a German newspaper estimated.

They were cheap to make, and unlike a vinyl record, it’s easy to re-record sound onto a tape.

For a time, not only did audiocassettes dominate the market, but they carried a huge significance for the culture.

Actors in ‘80s movies wielded tape decks and boom boxes to advance their storylines: "Say Anything," "Fame" and "Fatal Attraction" are just three examples among a horde.

Cassettes also played a central role in the development of hip-hop during its early years.

In 2011, rapper Nas told filmmakers with electronics company TDK that ‘80s-era audiocassettes were the key to learning how to write, perform and produce hip-hop. Musicians like Nas could meet for “park jam” sessions, then use cassettes to improve their chops.

“After park jam was over, you just had memories,” he said. “When you had a chance to have it on cassette, then you could sit there and really study it.”

By 1990, 442 million cassettes were sold, the Associated Press reported.

But the era of compact discs, then downloadable and streaming music, was at hand. By 2006, AP reported that only 700,000 cassettes were sold in the United States.

But, fueled by several factors, they started coming back in the second decade of the 21st century.

“Two formats are growing for indie and major record labels: audiocassettes and vinyl LPs,” Stepp said.

The demographic driving their growth has yet to celebrate its 35th birthday, he said.

“People raised on MP3s, with digital music consumed in earbuds — it’s a very sharp, crisp sound,” Stepp said. “But if you listen, the analog sounds better.”

Digital music lacks harmonics, Stepp explained, because file compression crams frequencies together. Analog offers depth, warmth, the chance for every note and frequency to sing out.

“There’s a dirty little secret here,” said the 69-year-old, an amused smile on his face. “We’ve got an advantage. Your ears are analog. The world is analog.”

Cassettes are also made of matter, not energy.

“You can’t hold a download in your hand,” Stepp said. “The physical nature of owning something tangible is a big deal.”

In 2014, National Audio produced 10 million cassettes, Forbes reported. In 2015, that number grew by 30 percent. The same year, Stepp told public radio's Marketplace that he believes the cassette market is growing by 20 percent per year.

Stepp told the News-Leader that 3,347 recording labels now buy National Audio Company cassettes and that audiocassettes make up 70 percent of its sales. (He declined to give out dollar figures.)

Those record labels include behemoths like Disney, which hired National Audio to produce “Guardians of the Galaxy” cassettes. They sold a million copies.

"Since 1994, that's been the biggest cassette for Disney," he said.

Along with Disney, Sony and Universal, National Audio also works with a host of small fry.

I'm fine thanks, a St. Louis-based independent music label, has fewer than 20 artists. But it puts out most of their work on cassette tapes, along with digital distribution.

Joe Bryant founded the label in 2015. He buys cassettes from several suppliers in addition to National Audio Company, at least one of which describes its cassette stocks as "close-out inventory."

Bryant told the News-Leader that nostalgia prompted him to release music on cassette. "It's a platform that I've personally always been sentimental with," he said in an email.

It's a cultural moment for nostalgia, as many of today's television, movie and music creators grew up in the '80s with cassettes as part of everyday life.

The soundtrack to Netflix hit "Stranger Things" came out on cassette in July, sold only in Urban Outfitters stores, reported Pitchfork. Cassettes featured prominently in prestige TV shows like HBO's "The Leftovers" and AMC's "Better Call Saul."

But as an independent label founder, Bryant is less bullish on the future of cassettes than Stepp, with National Audio Company.

"I feel like the trend is already in its decline back to novelty again," Bryant said. "I’ve seen quite a few other labels similar to i'm fine thanks dissolve over the past two years. I see the trend remaining for three to five more years."

But, Bryant predicted, cassettes will remain a novelty, and people will keep making them.

Stepp points out that National Audio has many long-term customers: the federal government, state-owned libraries for blind and visually impaired folks, religious institutions and customers seeking to restore taped materials from the 1960s and 1970s.

Stepp showed off the third-floor operation where National Audio records cassettes, then labels them and adds J-cards — the paper-stock covers that line a cassette's clear-plastic case.

“Get a good look," he said. "You’ll never see this again.”