Elmore County is located in the southern part of Idaho. It's county seat is Mountain Home. The 2010 census counted 27,038 residents.
Prior to the arrival of the first Anglo-Europeans, Elmore County was home to the Shoshoni and Bannock Indian Tribes. Both of these two peoples were nomadic hunters/gatherers and they followed their traditional food sources through the seasons. Winters were spent camping along the Snake River in what is today Elmore County. The first outsiders to arrive were fur trappers in the early decades of the nineteenth century. Although there were some individual conflicts between trapper and Indian, relations between the two groups was generally peaceable. Things began to change, however, as emigrants bound for California and Oregon started pouring through the area in the middle of the century. From that point forward, travelers, settlers and miners began contesting with Indians for control of the region's resources. Relations deteriorated.
Historians tell us that more than 250,000 emigrants passed through Elmore County between 1840 and 1862. One of the more important river crossings was located there. Three Island Crossing on the Snake River. The Oregon Trail was tough and Three Island Crossing was treacherous. Personal accounts describe an unbroken line of wagon trains that stretched for miles back from the crossing point. (Some of these writers also referred to the trail as being the longest cemetery in the world.) During this period of time few emigrants settled in Elmore County, but that changed in the early 1860's when gold was discovered in Rocky Bar and Atlanta. Among the more important mines in the area at the time the county was formed (1889) was the Ida Elmore Mines. The county took it's name from them.
Farmers, ranchers and townspeople followed the miners and gradually permanent settlements grew up. Toward the end of the nineteenth century, sheep herders and cattle ranchers fought it out much as was happening elsewhere in the western states. The economy boomed during World War I, but slumped badly afterwards. The Great Depression of the 1830's hit Elmore County hard and many residents lost everything. The economy began improving again with increased crop prices due to the advent of World War II. Today, Elmore County's most important economic resource is Mountain Home Air Force Base.