|Coordinates: 40°53′N110°58′W / 40.88°N 110.97°W Coordinates: 40°53′N110°58′W / 40.88°N 110.97°W|
|Named for||The summits of the mountains|
|Largest city||Park City|
|• Total||1,882 sq mi (4,870 km2)|
|• Land||1,872 sq mi (4,850 km2)|
|• Water||10 sq mi (30 km2) 0.5%|
|• Density||23/sq mi (8.7/km2)|
|Time zone||UTC−7 (Mountain)|
|• Summer (DST)||UTC−6 (MDT)|
Summit County is a county in the U.S. state of Utah, occupying a rugged and mountainous area. As of the 2010 United States Census, the population was 36,324.  Its county seat is Coalville,  and the largest city is Park City.
The county was created by the Utah Territory legislature on January 13, 1854, with its description containing a portion of the future state of Wyoming. It was not organized then but was attached to Great Salt Lake County for administrative and judicial purposes. The county government was completed by March 4, 1861, so its attachment to the other county was terminated. The county boundaries were altered in 1856 and in 1862. In 1868 the Wyoming Territory was created by the US government, effectively de-annexing all Summit County areas falling within the new territory. The boundaries were further altered in 1872 and 1880. Its final alteration occurred on January 7, 1918, when Daggett's creation took a portion of its eastern territory. Its boundary has remained unchanged since that creation.  It is so named because it includes 39 of the highest mountain peaks in Utah.
The county's mean elevation is 8,388 feet (2,557 m) above sea level, which is the second-highest (after Taos County, New Mexico) of any county outside Colorado.  Owing to its proximity to Salt Lake City, Park City has acquired a reputation as an upscale getaway, bringing new development to the area.
Summit County is part of the Heber, UT Micropolitan Statistical Area, which is also included in the Salt Lake City-Provo-Orem, UT Combined Statistical Area.
Summit County lies on the upper east side of Utah. Its northeast borders abut the south and west borders of the state of Wyoming. Its central and eastern portion consists largely of the east-west oriented Uinta Mountains, while its western portion runs to the east slopes of the north-south oriented Wasatch Mountains.  The county's highest point is Gilbert Peak, on the border with Duchesne County, at 13,448' (4099m) ASL.  The county has a total area of 1,882 square miles (4,870 km2), of which 1,872 square miles (4,850 km2) is land and 10 square miles (26 km2) (0.5%) is water. 
|US Decennial Census  |
1790–1960  1900–1990 
1990–2000  2010–2018  2019  2020 
As of the 2000 United States Census, there were 29,736 people, 10,332 households, and 7,501 families in the county. The population density was 15.9/sqmi (6.13/km2). There were 17,489 housing units at an average density of 9.34/sqmi (3.61/km2). The racial makeup of the county was 91.80% White, 0.24% Black or African American, 0.31% Native American, 0.96% Asian, 0.04% Pacific Islander, 5.43% from other races, and 1.21% from two or more races. 8.09% of the population were Hispanic or Latino of any race.
There were 10,332 households, of which 40.80% had children under 18 living with them, 63.50% were married couples living together, 6.20% had a female householder with no husband present, and 27.40% were non-families. 18.40% of all households were made up of individuals, and 3.20% had someone living alone who was 65 years of age or older. The average household size was 2.87, and the average family size was 3.30.
The median income for a household in the county was $64,962, and the median income for a family was $72,510. Males had a median income of $47,236 versus $28,621 for females. The per capita income for the county was $33,767. Only 42.9% are natives of Utah. 5.40% of the population and 3.00% of families were below the poverty line.
According to a 2000 survey by the Association of Statisticians of American Religious Bodies, Summit County is much more diverse in religious belief than Utah. Fully two in five people (44.2%) of the population claim no religion at all, while among those that do, The Church of Jesus Christ of Latter-day Saints (LDS Church) is the largest group at 36.8% (compared with some 66% statewide), followed by Roman Catholics at 10.6%.
Summit County has traditionally been a Republican stronghold. Since the 1990s, it has become more competitive due to the influence of Democrat-leaning Park City Since then; Democrats have at times won a plurality or even a majority of the countywide votes. In 1996, Bill Clinton became the first Democrat to win the county since Lyndon Johnson's 44-state landslide in 1964 and only the second Democrat to carry it since Franklin D. Roosevelt. Although George W. Bush carried the county in 2000 and 2004, his performance there was worst in the state. In a 2006 US Senate race, Summit County was the only county carried by Democrat Pete Ashdown even as the Republican incumbent Orrin Hatch carried the state as a whole by a 2 to 1 margin. Likewise, in the 2008 U.S. presidential election, Barack Obama carried the county by a 15.3% margin over John McCain, while McCain carried Utah by 28.1% over Obama.  However, in the 2012 presidential election, Republican Mitt Romney defeated Obama in the county, 51% to 46%.  In 2016, Democrat Hillary Clinton defeated Republican Donald Trump, 50% to 35%.  The county is no more Republican in gubernatorial politics. In both the 2012 and 2016 elections it was the only county to support the Democratic candidate over Gary Herbert.
|Senate||19||John D. Johnson||Republican||2020 |
|Senate||26||Ronald Winterton||Republican||2018 |
|House of Representatives||28||Brian King||Democrat||2008 |
|House of Representatives||53||Kera Birkeland||Republican||2020 |
|House of Representatives||54||Mike Kohler||Republican||2020 |
|Board of Education||7||Carol Lear||Democrat||2016 |
|Board of Education||12||James Moss Jr.||Republican||2020 |
In the 2016 Senate race, Summit County was the only county in Utah where a plurality voted for Democratic nominee Misty Snow against Republican incumbent Mike Lee. Snow was the first major-party transgender Senate candidate in United States history, making the county the first in the nation to vote for a transgender candidate for the Senate.
On the county level, most of the elected offices are held by Democrats, including four of the five seats on the newly created Summit County Council.  -John Hanrahan, D; Claudia McMullin, D; Sally Elliott, D; Chris Robinson, D; David Ure, R
Summit County was one of only two counties (along with Grand County) to vote against Utah's same-sex marriage ban in 2004. In June 2010, Summit County became the sixth local government of Utah to prohibit discrimination in employment or housing based on a person's sexual orientation or gender identity. 
There are three school districts covering sections of the county: 
Utah is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its west by Nevada. Utah also touches a corner of New Mexico in the southeast. Of the fifty U.S. states, Utah is the 13th-largest by area; with a population over three million, it is the 30th-most-populous and 11th-least-densely populated. Urban development is mostly concentrated in two areas: the Wasatch Front in the north-central part of the state, which is home to roughly two-thirds of the population and includes the capital city, Salt Lake City; and Washington County in the southwest, with more than 180,000 residents. Most of the western half of Utah lies in the Great Basin.
Davis County is a county in northern Utah, United States. As of the 2010 United States Census, the population was 306,479, making it Utah's third-most populous county. Its county seat is Farmington, and its largest city is Layton.
Daggett County is a county in the northeastern corner of the U.S. state of Utah. As of the 2020 United States Census, the population was 935, making it the least populous county in Utah. Its county seat is Manila. The county was named for Ellsworth Daggett, the first surveyor-general of Utah. The small community of Dutch John, located near the state line with Colorado and Wyoming, became an incorporated town in January 2016.
Carbon County is a county in the U.S. state of Utah. As of the 2010 United States Census, the population was 21,403. Its county seat and largest city is Price.
Box Elder County is a county at the northwestern corner of Utah, United States. As of 2018, the estimated population is 54,950. Its county seat and largest city is Brigham City. The county was named for the box elder trees that abound in the county.
Duchesne County is a county in the northeast part of the U.S. state of Utah. As of the 2010 United States Census, the population was 18,607. Its county seat is Duchesne, and the largest city is Roosevelt.
Emery County is a county in east-central Utah, United States. As of the 2010 United States Census, the population was 10,976. Its county seat is Castle Dale, and the largest city is Huntington.
Juab County is a county in western Utah, United States. As of the 2010 United States Census, the population was 10,246. Its county seat and largest city is Nephi.
Piute County is a county in south-central Utah, United States. As of the 2010 United States Census, the population was 1,556, making it the second-least populous county in Utah. The county seat is Junction, and the largest town is Circleville.
Rich County is a county in the U.S. state of Utah. As of the 2010 United States Census, the population was 2,264, making it the third-least populous county in Utah. Its county seat is Randolph, and the largest town is Garden City. The county was created in 1864. It was named for an early LDS apostle, Charles C. Rich.
Morgan County is a county in northern Utah, United States. As of the 2010 census, the population was 9,469. Its county seat and largest city is Morgan. Morgan County is part of the Ogden-Clearfield, UT Metropolitan Statistical Area as well as the Salt Lake City-Provo-Orem, UT Combined Statistical Area.
Salt Lake County is located in the U.S. state of Utah. As of the 2020 United States Census, the population was 1,185,238, making it the most populous county in Utah. Its county seat and largest city is Salt Lake City, the state capital. The county was created in 1850. Salt Lake County is the 37th most populated county in the United States and is one of four counties in the Rocky Mountains to make it into the top 100. Salt Lake County is the only county of the first class in Utah - under the Utah Code is a county with a population of 700,000 or greater.
Sanpete County is a county in the U.S. state of Utah. As of the 2010 United States Census, the population was 27,822. Its county seat is Manti, and its largest city is Ephraim. The county was created in 1850.
Wasatch County is a county in the U.S. state of Utah. As of the 2010 United States Census, the population was 23,530. Its county seat and largest city is Heber City. The county was named for a Ute Indian word meaning mountain pass or low place in the high mountains.
Utah County is the second-most populous county in the U.S. state of Utah. The county seat and largest city is Provo, which is the state's third-largest city, and the largest outside of Salt Lake County. As of the 2020 United States Census, the population was 665,665.
Uintah County is a county in the U.S. state of Utah. As of the 2010 United States Census the population was 32,588. Its county seat and largest city is Vernal. The county was named for the portion of the Ute Indian tribe that lived in the basin.
Wayne County is a county in the U.S. state of Utah. As of the 2010 census, the population was 2,778, making it the fourth-least populous county in Utah. Its county seat is Loa.
Weber County is a county in the U.S. state of Utah. As of the 2020 census, the population was 262,223, making it Utah's fourth-most populous county. Its county seat and largest city is Ogden, the home of Weber State University. The county was named for the Weber River.
The Wasatch Back is a region in the Rocky Mountains in the U.S. state of Utah. It includes cities such as Park City, Heber City, and Morgan. The name Wasatch Back differentiates it from the Wasatch Front, which includes Utah's more populous cities such as Salt Lake City, Ogden, Layton, and Provo. The Wasatch Back sits on the eastern side of the Wasatch Range of the Rocky Mountains, while the Wasatch Front sits on the western side. Wasatch is a Ute Indian word that means "mountain pass" or "low pass over high range." The Wasatch Back is a very affluent region. Summit County is one of the wealthiest counties in the United States.
State Route 248 is a highway in northern Utah that connects Park City with Kamas. In Park City it is known as Kearns Boulevard.