[2] Pando, a clonal quaking aspen stand, that, according to some sources, is the oldest (80,000 years) and largest (106 acres, 13 million pounds) organism on Earth, is located in this county.

In Utah, the Numic- (or Shoshonean) speaking peoples of the Uto-Aztecan language family evolved into four distinct groups in the historical period: the Northern Shoshone, Goshute or Western Shoshone, Southern Paiute, and Ute peoples.

[5] The first modern sighting of the Sevier River was most likely by the Catholic fathers Silvestre Vélez de Escalante and Francisco Atanasio Domínguez, on their expedition to California in 1776.

Over the next century, this trail carried fur trappers, hunters, government officials, traders, and settlers.

Mormon settlers (The Church of Jesus Christ of Latter Day Saints) arrived on June 15, 1864, most of whom had emigrated from Scandinavian countries.

Because of the growth in this small community, the people soon petitioned Utah Territory officials about a separate county.

[10] Sevier County terrain consists of semi-arid but arable rolling areas punctuated by northeast–southwest mountain ridges, usually forested.

[11] The highest point is Fish Lake Hightop in the Central Utah Plateau, at 11,633 ft (3,546 m) ASL.

As Richfield is about halfway between the major cities of Los Angeles, California and Denver, Colorado, it has built a hospitality industry, with motels and restaurants serving travelers.