According to The Public Domain Review, Wizard of Oz author L. Frank Baum’s 1902 The Life and Adventures of Santa Claus, “with its elaborations and much added detail went a long way to popularising the legend of Santa”. You can read the entire book online and in various other formats including ePUB and Kindle at Project Gutenberg.
First Edition 1902
Multiple editions on Goodreads.
The Public Domain Review: A Pictorial History of Santa Claus.
Beyond Survival in a School Library 