The Colorado Postal Encyclopedia is the initial work by Bill Bauer. The encyclopedia contains descriptions of all locations in Colorado that had, or have, a post office. In addition, the Encyclopedia contains tracings of known postal markings and dates of known usage to 1959. After Bauer's untimely death, the final chapters of the printed copy were organized for publication by Steve Morehead, Roger Rydberg and Joe Coston. Upon completion of the printed copy, Steve Morehead offered to review the Encyclopedia, add additional information, and create a digital version of the Encyclopedia. Roger Rydberg and Joe Ditlow assisted in this project. Joe has continued to produce an addenda of new finds and Roger has added the digital version to the Colorado Postal History Society website.