What happens to the books that don’t sell?

Unsold books are boxed up for ThriftBooks.
MainFloorDS General book sale. The books offered at each sale come from the previous six months’ donations. Every sale starts from scratch! After each sale, volunteers spend a day taking unsold books from the shelves and filling enormous boxes (see photo above: using FOL volunteer Barbara Need, front left, in the teal apron, as a unit of measurement, each of the boxes is nearly one Barbara tall) with them for delivery to Thrift Books. Some of these books are donated to charities dedicated to fighting illiteracy: through the efforts of Thrift Books and its not-for-profit literacy partners more than a million books have been donated and distributed to countries in Africa and Asia. Others are sold via the Thrift Books online store: a percentage of the proceeds from these sales comes back the the Friends, where it helps support libraries and charitable organizations in Tompkins County.
ColCorDS Collector’s Corner. Donated books that are selected for the Collector’s Corner are held for two sales, as the audience for the Fall and Spring Sales tends to differ. After a book has been through two sales, appraisers in Collector’s Corner re-evaluate it. Some are moved to the general sale floor. Others — textbooks and non-vintage books — are sent directly to Thrift Books or offered for sale on Amazon.com. Some particularly valuable titles are sent to auction (Christie’s Auction House in New York and National Book Auctions of Danby).