Walkman
Audio cassettes have seen a recent bump in popularity. Reuters

Vinyl records may be a hipster obsession or a legitimate alternative to digital, and now the same may be said for audio cassettes. You may not know it, but the National Audio Co. is still operating, producing millions of audio cassettes annually. Bloomberg Business has a great tour of the company in a new video.

"The Last Audio Cassette Factory" is what Bloomberg calls National Audio Co.'s plant in Springfield, Missouri. The company manufactures audio cassettes, cassette packaging and duplication. If you need a device on which to play your new tape, the company has you covered with a Coby Walkman- style compact stereo cassette player for $10. The National Audio Co. does have its foot in the modern era with CD, DVD and BLU-Ray products, but made a name for itself with tapes.

Steve Stepp, National Audio Co. president, said the company is making more tapes than ever. Stepp said National Audio Co. refused to give up on tapes and would buy up competitors as they transitioned to digital duplication. He had a hunch the music business would return to audio cassettes in some capacity and his gamble paid off.

The technology and machines that manufacture and duplicate audio cassettes are vintage and none of those companies is in business. Fixing the machines requires salvaging parts from nonoperational equipment. National Audio Company's chief technician may be the only person who understands how an electromagnetic tape recorder works, but he's training someone to take over.

Nostalgia is a huge part of the booming tape business, and National Audio Co.'s recent clients include Marvel for "Guardians of the Galaxy" and Metallica. In 2014, the company produced 10 million tapes.