(SOUNDBITE OF JACK WHITE SONG, "HIGH BALL STEPPER")
RENEE MONTAGNE, HOST:
This is the song "High Ball Stepper" from Jack White's album "Lazaretto." It sold 86,000 copies, making it the top-selling album last year on vinyl at a time when old-fashion record albums are having a resurgence. Lydia Emmanouilidou has more.
ANGELA SAWYER: All right, that is 54.75.
LYDIA EMMANOUILIDOU, BYLINE: Angela Sawyer is the owner of Weirdo Records in Cambridge, Mass.
SAWYER: I've been working in record stores around town for about 25 years.
EMMANOUILIDOU: Sawyer says there has been resurgence of vinyl in recent years, but...
SAWYER: When people talk about a surge in the vinyl industry, they're talking about from flat line zero to a tiny blip. And neither of those have anything on, say, the number of Eagles records that were pressed in the '70s.
EMMANOUILIDOU: And she's right. Billboard reports vinyl sales hit a record high in 2014, up 52 percent over the previous year. But that's still less than 4 percent of all album sales that year. Still, even that tiny bump is keeping the plants where records are made very busy.
JAY MILLAR: We've been running at capacity for quite some time.
EMMANOUILIDOU: That's Jay Millar of United Record Pressing in Nashville, Tenn. The plant is running at capacity because it's just one of about 16 vinyl press plants still operating in the U.S. Millar says they're pushing records out their doors as fast as they possibly can.
MILLAR: We average 30 to 40,000 records a day, six days a week, 24 hours a day on average.
EMMANOUILIDOU: But at United and other pressing plants throughout the country, you won't find your typical assembly line.
MILLAR: It's a very, very human process.
EMMANOUILIDOU: Millar says aspects of the process are automated, but for the most part, assembly is done by hand.
MILLAR: The records accumulate on a press and, you know, stack up on a spike, where an inspector comes up and grabs those, by hand, off the press, takes them to an inspecting table, where each record gets visually inspected one by one. And then we also listen completely to about one record per press per hour.
EMMANOUILIDOU: That degree of human touch is what's keeping Matt Earley of Gotta Groove Records in Cleveland, Ohio, from expanding hours of operation at his plant, even in the vinyl boom.
MATT EARLEY: It's something that we may have to do at some point, but we've resisted it thus far, mainly because how hands-on and how much human intervention there is in making good records.
EMMANOUILIDOU: He says finding people who can do the job well is no easy task because...
EARLEY: Really, it's an art. It's something that it takes a while to learn.
EMMANOUILIDOU: And the machines that press the vinyl are even harder to come by than the people who know how to operate them. Again, Jay Millar of United Record Pressing.
MILLAR: We're operating currently 28 presses. So if the largest has 28 presses, it's not a real enticing thing for the company to try and create more presses.
EMMANOUILIDOU: Instead, United has been acquiring and restoring used pressing equipment from closed plants.
MILLAR: We've gotten some from as far away as Italy. It's just whenever one would hit the market, we'd do our best to snap it up in anticipation of all this growing.
EMMANOUILIDOU: And United is banking on that growth. It plans to open another vinyl pressing plant later this year. For NPR News, I'm Lydia Emmanouilidou in Boston. Transcript provided by NPR, Copyright NPR.