Geocaching was originally similar to the game letterboxing (which originated in 1854), which uses clues and references to landmarks embedded in stories. Geocaching was conceived shortly after the removal of Selective Availability from the Global Positioning System on May 2, 2000, because the improved accuracy of the system allowed for a small container to be specifically placed and located. The first documented placement of a GPS-located cache took place on May 3, 2000, by Dave Ulmer of Beavercreek, Oregon. The location was posted on the Usenet newsgroup sci.geo.satellite-nav at . Within three days, the cache had been found twice, first by Mike Teague. According to Dave Ulmer's message, this cache was a black plastic bucket that was partially buried and contained software, videos, books, money, a can of beans, and a slingshot.