Island Park Idaho Historical Society

By Donald B. Lindsey, Ph.D.

Island Park is a unique historical and geological area in north Fremont County, Idaho. The area covers a wide strip from what is locally known as the Ashton Hill to the Montana border, in a shallow high altitude basin formed by an ancient caldera.

Within the area is a city by the name of Island Park that was incorporated in 1947 because Idaho’s liquor laws required a city for the purpose of regulation. The city lines were drawn around existing lodges along the old Highway 20. This gives the city a peculiar configuration, and the distinction of having “the longest Main Street in America.”

“Main Street,” or U. S. Hwy 20 in Island Park, is 33 miles long from Last Chance to Valley View. Its width, however, is only an average of 500 feet from the center line of the old highway, where most businesses serving spirits exist, plus extensions to the west that reach Staley Springs and to the east that reach Big Springs.

Island Park was named for its many natural clearings, some bounded by water, that appear in this otherwise heavily timbered area. These openings in the forest were likened to islands where travelers could stop and “park” to rest or otherwise transact their business. The first humans to do this were members of various Native American tribes: the Blackfeet, the Bannock, the Crow, the Flatheads, and bands of the Shoshone Tribe, including the Sheepeater band.

Next came the first trappers and traders, followed by explorers, guides, and scouts beginning with the summer of 1810. The first of these was Major Andrew Henry, for whom Henry’s Lake is named, and the North Fork of the Snake River that is often referred to as Henry’s Fork of the Snake. The most famous of these early visitors include Jim Bridger, George Rea, Kit Carson, Richard “Beaver Dick” Leigh and Richard W. “Dick” Rock (Rocky Mountain Dick). Of these, Dick Rock and George Rea settled in the area to ranch, hunt, and serve as guides.

Other settlers arrived during the late 1860s, homesteaded, and began to build ranches and engage in other business. Such enterprises included mining, cutting timber, road building, and fish harvesting. Still other businesses were geared to accommodating sportsmen and travelers headed for Yellowstone National Park. Island Park has thus served as an important gateway to Yellowstone since 1872, and significantly helped in opening the park’s west entrance.

Today, Island Park still serves as a gateway to Yellowstone and many of its people work in the tourism industry. In its own right, Island Park is a prime recreation area for those who love to camp, hike, fish, hunt, float rivers, view wildlife, snowmobile, cross country ski or simply view majestic scenery. Island Park is also increasingly becoming a choice summer home area and a retirement area for those who don’t mind more than a little snow.

Geologically, about 500,000 years ago much of what now forms the Island Park area was a large volcano that exploded with extraordinary force. Geologists tell us that fallout from that event has been found as far away as Kansas.

In the aftermath of that explosion, Island Park was left with a world class U-shaped volcanic caldera formation. A caldera is a volcanic crater that has a diameter several times that of the vent and is formed by the collapse of the central portion of the volcano. The Island Park caldera measures 18 miles in width and is 23 miles long. Since that ancient time the crater has largely been filled in by lava flows from the east in Yellowstone National Park. In addition, other elements of nature helped set the stage for the historical developments of Island Park by humans.

Both the Nez Perce and the U.S. Army spent time at this shallow lake located in a grassy, seven mile wide basin surrounded by mountains. Nearby Raynold’s Pass funnels traffic on State Hwy 87 to the north towards Bozeman or Ennis, MT while US Hwy 20 crosses Targhee Pass at the Continental Divide and leads to West Yellowstone. As State Hwy 87 passes the north shore of Henrys Lake it meets Forest Road 55, which continues around the lake to Staley Springs. This is where Gilman Sawtell, the first homesteader in Island Park, bivouacked General Howard’s troops while the general rode to Virginia City for supplies.

A loop can be made around the lake by continuing on to Forest Road 53. The road ends at US Hwy 20 and is a lovely drive on a dirt road.

Island Park was named for its many natural clearings, some bounded by water, that appear in this otherwise heavily timbered area. These openings in the forest were likened to islands where travelers could stop and “park” to rest or otherwise transact their business. The first humans to do this were members of various Native American tribes: the Blackfeet, the Bannock, the Crow, the Flatheads, and bands of the Shoshone Tribe, including the Sheepeater band.

Next came the first trappers and traders, followed by explorers, guides, and scouts beginning with the summer of 1810. The first of these was Major Andrew Henry, for whom Henry’s Lake is named, and the North Fork of the Snake River that is often referred to as Henry’s Fork of the Snake. The most famous of these early visitors include Jim Bridger, George Rea, Kit Carson, Richard “Beaver Dick” Leigh and Richard W. “Dick” Rock (Rocky Mountain Dick). Of these, Dick Rock and George Rea settled in the area to ranch, hunt, and serve as guides.

Other settlers arrived during the late 1860s, homesteaded, and began to build ranches and engage in other business. Such enterprises included mining, cutting timber, road building, and fish harvesting. Still other businesses were geared to accommodating sportsmen and travelers headed for Yellowstone National Park. Island Park has thus served as an important gateway to Yellowstone since 1872, and significantly helped in opening the park’s west entrance.

Source: Donald B. Lindsey, Ph.D. - Island Park Historical Society