WILLOW CREEK — What began decades ago as a penny-per-guess betting pool on a napkin has become a revenue-generating tourism event, with official Homan’s Pond Ice-Out merchandise sales hitting $18,000 for the 2023 season.

The Carnegie Library, which took over administration of the ice-out contest in 2019, sold 420 commemorative T-shirts, 230 hats, and 150 ceramic mugs featuring the winning 2023 date — April 4 at 2:15 p.m., correctly predicted by three contestants who split the $500 cash pool.

But the real money has been in merchandise. Library director Doris Kim said proceeds from the ice-out line have funded a children’s reading program and new shelving in the local history room.

“This is the kind of low-stakes civic silliness that builds community identity,” Kim said. “And it turns out people from away want a piece of that identity.”

Merchandise sales are shipped to buyers in 14 states, with the largest out-of-state orders from former Maine residents living in Florida and Arizona.

The General Store stocks the merchandise year-round, and Maeve O’Donnell said ice-out gear has become a top seller among visitors who miss the contest date.

“The people who get it are passionate about it,” O’Donnell said. “They’ll drive from Bangor just to buy a hat and ask when next year’s contest starts.”

The library plans to expand the merchandise line to include hoodies and stickers for the 2024 season.