Gardiner is a census-designated place (CDP) in Park County, Montana, United States, along the 45th parallel. The population was 851 at the 2000 census.
Gardiner was officially founded in 1880, but the area has served as a main entrance to Yellowstone National Park since its creation in 1872. Parks' Fly Shop, one of the oldest fly shops and guiding operations in the Yellowstone area, was started by Merton Parks in 1953. Yellowstone National Park Heritage and Research Center, which opened May 18, 2005 is located in Gardiner, MT and houses National Park Service archives, Yellowstone museum collections and reference libraries,.
The name Gardiner derives from Johnson Gardner, a fur trapper who operated in the area in 1830-31. He named the lush headwaters valley of today's Gardner River Gardner's Hole. Originally, named Gardner's Fork, the river took on Gardner's name although prospectors and explorers who visited the area later in the century were unaware of the trapper Johnson Gardner. In 1870, when the Washburn-Langford-Doane Expedition passed through the area they began calling the river Gardiner--a phonetic error. Hiram M. Chittenden (1895) and Nathaniel P. Langford (1905) confirmed this spelling in their accounts of the expedition.