Canadian book distributors have been busy this holiday season keeping up with demand for what booksellers are calling “the never-ending colouring-book craze.”

Catherine Slavin, a representative for Toronto-based distributor North 49 Books, says the company started carrying colouring books aimed specifically at the adult market last year, and has sold more than 20,000 since June.

“When you combine the more than 80 types of colouring books we’ve had, then you do have the top seller for us this year,” she says. “They eclipse all the other titles for the year. Our top two non-colouring book titles are Paula Hawkins’s Girl on the Train and Anthony Doerr’s All the Light We Cannot See at 10,000 copies each.”

Sales for pencil crayons, which North 49 began carrying for the first time in 2015, have been likewise successful. “We’ve also sold 10,000-plus packs of pencil crayons this year, something we sold zero of last year. Both of our suppliers, Staedlter and Crayola, are mostly out of stock until next year,” Slavin says.

The trend was arguably spurred by Scottish illustrator Johanna Basford’s 2013 volume Secret Garden: An Inky Treasure Hunt and Colouring Book, which Slavin says has “of course” sold the best, followed by media tie-in titles for Harry Potter, Star Wars, and Game of Thrones. North 49 has also sold out of urban geographer Daniel Rotsztain’s All the Libraries Toronto, which Dundurn Press released in October.

Raincoast Books vice-president of sales Peter MacDougall says the Vancouver distributor has also moved thousands of The Secret Garden since the trend really picked up in the spring, along with strong numbers for dozens of other titles, many of them from Basford’s U.K. publisher, Laurence King.

“You can see from the BookNet numbers alone that several are doing as much as 5,000 to 10,000-plus. The Secret Garden is among a very few at the top that created the phenomenon, along with Basford’s follow-up, Enchanted Forest,” MacDougall says. “The colouring-book craze has felt at times like other blockbuster phenomena, but it’s been so widespread across so many titles and so many market segments; a true gift for the entire industry. The biggest challenge has been staying ahead with all retail channels seeing huge demand.”

During the busy holiday-shopping season, The Secret Garden and other adult colouring books consistently dominated Amazon.ca’s bestseller list and retailer window displays. As the year draws to a close, distributors are optimistic that demand for the titles won’t wane anytime soon.

“We were going to wait and see if this will last past Christmas, but I do believe it will continue for a bit yet, as I see the big stores and media outlets are just starting to notice it,” Slavin says.

MacDougall agrees, saying Raincoast expects the trend to continue into the new year. “[Certain colouring books] tie in so nicely to make them perfect for both merchandising opportunities in stores and for people to hunker down with during the winter to see what all the fuss is about.”