In May of 1832, Captain Benjamin Bonneville left Fort Osage, Missouri with an expedition consisting of one hundred and ten men and twenty wagons, headed for the Rocky Mountain West. Upon his arrival in the Green River Valley, he ordered immediate construction of a fort along the west bank of the River. Some uncertainty surrounds Bonneville's intent, but historians believe it was to use the fort as a trading establishment and military outpost to demonstrate to the British that Americans were in the west to stay.
Dubbed "Fort Nonsense" and "Bonneville's Folly" because of its poor location, the fort was soon abandoned as the severity of long Wyoming winters became apparent. However, the fort commanded a strategic location in the heart of the Rocky Mountain Trapping System. In 1833 it was the center of trading activity for the annual rendezvous and for storage of the 1836 Rendezvous.
The fort was fabricated of cottonwood pickets a foot or more in diameter and about fifteen feet in length. The perimeter was approximately eighty feet square, with blockhouses diagonally opposite each other. It had at least one internal structure which housed a forge that was used extensively during the fort's occupation.
In 1989, an archeological survey was conducted at the site as one of Wyoming's Centennial celebration projects. The effort produced evidence of a well defined "living surface", and discovery of the external walls. The fort's forge area was investigated, showing active and extensive blacksmithing. Numerous early 1800s artifacts were unearthed, revealing much about Fort Bonneville's archeological significance as well as its historic contribution to events of the Fur Trade Era. These artifacts are on exhibit and interpretation at the Museum of the Mountain Man in Pinedale, Wyoming.
Completed in September 1832, Fort Bonneville was one of the first permanent structures built by whites in Wyoming. The location and the archeological remains are a listed National Historic Place.