Sevier County (/sɛˈvɪər/ sə-VEER) is a county in Utah, United States. As of the 2020 United States Census, the population was 21,522. Its county seat and largest city is Richfield.

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.

Evidence of indigenous peoples residing in Sevier County up to 5,000 BP has been unearthed. The Fremont culture of Native Americans occupied the area from about 2000 to 700 BP. The Clear Creek site contains native petroglyphs from that period.

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. This territory's central and eastern sections were occupied primarily by various bands of the Ute.

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. The Old Spanish Trail was the route they mapped. Over the next century, this trail carried fur trappers, hunters, government officials, traders, and settlers.

Settlement of this area began when Richfield was first settled. 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.

On January 16, 1865, the Utah Territory legislature created the county, with the area annexed from Sanpete County. It was named for the Sevier River. The county seat was Big Spring (later named Richfield). The county borders were adjusted in 1866, 1880, 1890, and in 1921. A clarification of boundary lines corresponding to government survey lines was completed in 1931, marking the present configuration of Sevier County.

Although the county was in place by 1865, much of Sevier County was abandoned in the Black Hawk War in 1867. Attempts to resettle the area were not successful until 1870. By 1874, 753 residents lived in the area.

Sevier County terrain consists of semi-arid but arable rolling areas punctuated by northeast–southwest mountain ridges, usually forested. The highest point is Fish Lake Hightop in the Central Utah Plateau, at 11,633 ft (3,546 m) ASL. The county has a total area of 1,918 square miles (4,970 km), of which 1,911 square miles (4,950 km) is land and 7.8 square miles (20 km) (0.4%) is water.

• Sanpete County – north
• Emery County – east
• Wayne County – southeast
• Piute County – south
• Beaver County – southwest
• Millard County – west

Historical population

Census	Pop.	Note	%±
1870	19		—
1880	4,457		23,357.9%
1890	6,199		39.1%
1900	8,451		36.3%
1910	9,775		15.7%
1920	11,281		15.4%
1930	11,199		−0.7%
1940	12,112		8.2%
1950	12,072		−0.3%
1960	10,565		−12.5%
1970	10,103		−4.4%
1980	14,727		45.8%
1990	15,431		4.8%
2000	18,842		22.1%
2010	20,802		10.4%
2020	21,522		3.5%
US Decennial Census 1790–1960 1900–1990 1990–2000 2010 2020

According to the 2020 United States census and 2020 American Community Survey, there were 21,522 people in Sevier County with a population density of 11.3 people per square mile (4.3/km). Among non-Hispanic or Latino people, the racial makeup was 19,396 (90.1%) White, 65 (0.3%) African American, 313 (1.5%) Native American, 40 (0.2%) Asian, 49 (0.2%) Pacific Islander, 49 (0.2%) from other races, and 557 (2.6%) from two or more races. 1,053 (4.9%) people were Hispanic or Latino.

There were 10,870 (50.51%) males and 10,652 (49.49%) females, and the population distribution by age was 6,449 (30.0%) under the age of 18, 11,325 (52.6%) from 18 to 64, and 3,748 (17.4%) who were at least 65 years old. The median age was 36.3 years.

There were 7,464 households in Sevier County with an average size of 2.88 of which 5,555 (74.4%) were families and 1,909 (25.6%) were non-families. Among all families, 4,491 (60.2%) were married couples, 362 (4.8%) were male householders with no spouse, and 702 (9.4%) were female householders with no spouse. Among all non-families, 1,640 (22.0%) were a single person living alone and 269 (3.6%) were two or more people living together. 2,777 (37.2%) of all households had children under the age of 18. 5,752 (77.1%) of households were owner-occupied while 1,712 (22.9%) were renter-occupied.

The median income for a Sevier County household was $55,361 and the median family income was $62,058, with a per-capita income of $24,041. The median income for males that were full-time employees was $50,183 and for females $36,000. 14.3% of the population and 12.3% of families were below the poverty line.

In terms of education attainment, out of the 13,469 people in Sevier County 25 years or older, 1,206 (9.0%) had not completed high school, 4,206 (31.2%) had a high school diploma or equivalency, 5,242 (38.9%) had some college or associate degree, 1,931 (14.3%) had a bachelor's degree, and 884 (6.6%) had a graduate or professional degree.

Interstate 70 runs through the county. 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.

Fremont Indian State Park is found in the Clear Creek Canyon, adjacent to I-70. It is noted for its archaeological remains from the ancient Native American Fremont culture. Its museum displays found artifacts.

Sevier County is traditionally Republican. In no national election since 1936 has the county selected the Democratic Party candidate (as of 2020).

State Elected Offices

Position		District	Name	Affiliation	First Elected
	Senate	24	Derrin Owens	Republican	2020
	House of Representatives	70	Carl Albrecht	Republican	2016
	House of Representatives	73	Phil Lyman	Republican	2018
	Board of Education	14	Mark Huntsman	Nonpartisan	2014

United States presidential election results for Sevier County, Utah

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	9,052	87.35%	1,084	10.46%	227	2.19%
2016	6,740	77.52%	695	7.99%	1,260	14.49%
2012	7,207	89.32%	738	9.15%	124	1.54%
2008	6,394	79.35%	1,359	16.87%	305	3.79%
2004	6,597	86.34%	920	12.04%	124	1.62%
2000	5,763	81.43%	1,046	14.78%	268	3.79%
1996	4,031	65.79%	1,327	21.66%	769	12.55%
1992	3,160	50.50%	1,039	16.60%	2,059	32.90%
1988	4,747	76.31%	1,403	22.55%	71	1.14%
1984	5,736	83.49%	1,072	15.60%	62	0.90%
1980	5,614	80.79%	1,112	16.00%	223	3.21%
1976	3,686	65.24%	1,564	27.68%	400	7.08%
1972	3,700	72.96%	820	16.17%	551	10.87%
1968	3,190	67.24%	1,167	24.60%	387	8.16%
1964	2,617	57.33%	1,948	42.67%	0	0.00%
1960	3,166	65.18%	1,690	34.80%	1	0.02%
1956	3,646	74.74%	1,232	25.26%	0	0.00%
1952	3,996	73.44%	1,445	26.56%	0	0.00%
1948	2,791	58.76%	1,943	40.91%	16	0.34%
1944	2,345	52.76%	2,095	47.13%	5	0.11%
1940	2,703	51.70%	2,521	48.22%	4	0.08%
1936	1,899	39.84%	2,816	59.07%	52	1.09%
1932	2,225	48.44%	2,303	50.14%	65	1.42%
1928	2,424	63.13%	1,399	36.43%	17	0.44%
1924	2,111	56.44%	1,201	32.11%	428	11.44%
1920	2,506	62.84%	1,425	35.73%	57	1.43%
1916	1,720	44.79%	2,052	53.44%	68	1.77%
1912	1,452	41.90%	915	26.41%	1,098	31.69%
1908	1,780	54.94%	1,272	39.26%	188	5.80%
1904	1,725	59.10%	930	31.86%	264	9.04%
1900	1,581	54.82%	1,261	43.72%	42	1.46%
1896	497	21.10%	1,858	78.90%	0	0.00%

All of the county is in the Sevier School District.

• National Register of Historic Places listings in Sevier County, Utah

• Official website