Inside an unmarked warehouse in a nondescript industrial park sits the largest machine of its kind anywhere in North America, a whiz-bang contraption of zigzagging conveyor belts, robot arms, bar codes, bins, scanners and pure logistic efficiency.
This is the King County Library System's new book-sorting machine, the hub of a system that distributes millions of books a year to hundreds of thousands of people at 50 library branches around the county.
In operation since June, the new machine replaced one that was nearly a quarter-century old and prone to breakdowns. The manufacturer, Lyngsoe Library Systems, told the county that the new $5.2 million machine is the largest library materials sorting system" in North America.
King County Library System is, in terms of circulation (the number of items checked out) close to twice as large as the Seattle Public Library. It lent out about 22.5 million items (books, e-books, CDs, etc.) in 2024, about 11.5 million physical items and about 11 million electronic.
It is, improbably, the second-largest public library in the United States by circulation, according to the Institute of Museum and Library Services, trailing only the Los Angeles Public Library. Third place, again improbably, goes to the Cincinnati & Hamilton County Public Library, followed by libraries in Minneapolis, Houston, New York and San Francisco. The Seattle Public Library is 10th. (New York City is served by three public library systems, so its numbers get divvied up.)
"We tend to outcirculate even our much larger cities, and I would put that up to the fact that this is a highly literary, book-oriented, community," said Heidi Daniel, executive director of the King County Library System.
The King County Library System serves rural areas and 35 of the county's 39 cities (Seattle has its own library, Milton uses the Pierce County Library and Hunts Point and Yarrow Point go without library service). Unlike The Seattle Public Library, it is an independent entity, self-funded and does not receive funding from King County government.
The library gets most of its money from a property tax levy that was last renewed in 2010. Library leaders are now considering asking voters — likely next year — for a levy renewal and increase.
"We have 50 buildings, the maintenance of our locations is obviously expensive," Daniel said. "But it's also thinking about how those buildings serve the public today, versus even 20 years ago, is very different."
A levy proposal would be voted on by King County voters, excluding Seattle, making approval less of a sure thing than many other recent levies that have sailed to passage.
Daniel said they want to provide better early-learning spaces and programs for children. And they want to be thought of as a third place — not work, not home, but one where you don't have to buy anything to hang out.
"We're not going to make you buy a latte, we're not going to make you have a subscription," she said. "We just want you to come in our doors."
The machine
King County's old sorter, informally dubbed the Tin Man, had been in service for more than 20 years and frequently broke. Technicians often had to scour the internet for replacement parts.
"I'll be out public speaking and people will be like 'I requested this book and it said "in transit" and it's been in transit for like two months,' " Daniel said. "And I'm like, 'Yeah, so, here's what happened. Our sorter broke down. We're waiting for an eBay part. It didn't get sorted correctly.' "
"That won't be happening anymore," she said. "People are going to get their books faster."
The old machine, which lived in Preston and has recently been disassembled, was also less pleasant to be around for the dozen or so people who worked with it every day, said Charlie Mitchell, the library's warehouse operations manager. It was noisier and required workers to do more bending down and heavy lifting.
The new machine lives inside a leased 25,000-square-foot warehouse.
A maze of multidirectional conveyor belts can move, at max output, up to 8,000 books, CDs and DVDs an hour from one gray plastic bin to another, each one barcoded and labeled and ready to be sent to a specific library, from Enumclaw to Richmond Beach, Federal Way to Skykomish.
Every time someone places a hold on a book or returns one to a different library than they checked it out from, that book will come through the machine.
"It's what puts a hold in your hands," Daniel said. "It takes it from shelf to customer."
Everything is transported in identical gray plastic totes with folding lids, each about the size of a foot locker.
Beginning at 5 a.m., seven days a week, trucks drop off totes full of books at the Renton warehouse and pick up presorted books to distribute, on five routes, to the county's 50 library branches (only Vashon-bound books get to take a ferry ride).
"We can pick up a book at a library on a Monday, sort it on a Tuesday, and it can be back in the destination library on Wednesday," Mitchell said. "If you were sorting that by hand, it'd probably take 10 days to get that same book."
Between drop-off and pickup is the machine. The totes are loaded on conveyor belts. Two robotic arms — metal limbs, plastic hinges, vaguely dystopian — transfer each tote to another rolling belt. The bins are unpacked by human workers who place each book (or CD or DVD) onto another system of belts and ramps.
Stand and watch a minute. The titles speak to the diversity of the library system's 3.9 million-item collection and to the varied interests of 704,000 residents with active library cards.
A worker unloads "Invent Your Own Computer Games with Python." There goes "Stitching Pathways: Successful Quilting on Your Home Machine." Right behind it: "Bleak House," Charles Dickens' epic of inheritance, love and lawyers.
Each title just read or about to be.
Each book is scanned by its barcode and then begins its own journey on a highway system of multidirectional belts and interchanges. There are ramps, overpasses, 90-degree turns.
There goes Season 1 of "Couples Therapy."
"Something from Nothing," the new Alison Roman cookbook, just took a left, on its way to the Black Diamond Library. "Don't Let the Pigeon Stay up Late" is heading to a (presumably) young reader in Des Moines.
Around 25,000 books and other pieces of physical media pass through the machine each day.
There goes "My Big Fat Greek Wedding," on its way to a viewer at the Boulevard Park Library in Burien. And "Black Leopard, Red Wolf, Marlon James' tale of mercenaries, fantasy and African history, on its way to Skyway.
Each book is eventually spit off the machine, back into one of the ubiquitous gray bins, ready to be loaded back onto a truck and sent back to its home library or to its next reader.
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