Island Park is a city in Fremont County, Idaho, United States. The city's population was 286 at the 2010 census, up from 215 in 2000. The city was incorporated by owners of the many lodges and resorts along U.S. Route 20 in 1947, primarily to circumvent Idaho's liquor laws that prohibited the sale of liquor outside of city limits. It is only wide in most locations yet, at , claims to have the longest "Main Street" in the world. Island Park is part of the Rexburg Micropolitan Statistical Area. Geography City geography Island Park is located at (44.4996, −111.3387), at an elevation of above sea level, making it the highest city in Idaho. According to the United States Census Bureau, the city has a total area of , of which, is land and is water. Regional geography The area was known as Island Park long before the -long town was incorporated. The area known as Island Park is mostly a large crater or caldera named the Henry's Fork Caldera that was created by the same hotspot that created the earlier Island Park Caldera and the later Yellowstone Caldera. In addition to the portion which lies on the Henry's Fork Caldera, about a third of what is known as Island Park is north of the caldera, extending across Henry's Lake Flat and Henry's Lake towards the Idaho/Montana border. Henry's Lake Flat is a flat bottomed valley between high mountain ranges, with Henrys Lake at the northwest end of the flats. Mount Jefferson, south of Henry's Lake, is high and Targhee Peak, north of Henrys Lake is high. The most famous of Island Park's peaks, however, is the Sawtell Peak, south of Henrys Lake near Mount Jefferson. The peak is known for its beauty and is named for a perceived resemblance to a Native American chief's profile while napping. The peak has also been called Chief Rains in the Face. Sawtell Peak is topped by a FAA radar dome and is visible from nearly anywhere in Island Park. Although much smaller than either the Island Park Caldera or the Yellowstone Caldera, the Henry's Fork Caldera is still one of the largest calderas in the world and is the only large caldera in the Yellowstone region that is plainly visible. It has a nearly level wide circular floor that slopes slightly towards the southeast. The caldera floor is at about of elevation with