 The Teton Valley was discovered by John Colter in 1808, a member of the Lewis and Clark Expedition (1804–06).It became known as Pierre's Hole, and it hosted the well-attended 1832 Rendezvous, which was followed by the Battle of Pierre's Hole.According to the U.S. Census Bureau, the county has a total area of , of which is land and (0.2%) is water.