From the Glenn Fleishman at The Atlantic:
The Great American Novel enters the public domain on January 1, 2019—quite literally. Not the concept, but the book by William Carlos Williams. It will be joined by hundreds of thousands of other books, musical scores, and films first published in the United States during 1923. It’s the first time since 1998 for a mass shift to the public domain of material protected under copyright. It’s also the beginning of a new annual tradition: For several decades from 2019 onward, each New Year’s Day will unleash a full year’s worth of works published 95 years earlier.
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Source: A Mass of Copyrighted Works Will Soon Enter the Public Domain – The Atlantic