Summit County is a county in the U.S. state of Utah, occupying a rugged and mountainous area. As of the 2020 United States Census, the population was 42,357. 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 Wyoming's southern and western borders. 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 ft (4,099 m) ASL. The county has an area of 1,882 square miles (4,870 km), of which 1,872 square miles (4,850 km) is land and 10 square miles (26 km) (0.5%) is water.

Historical population

Census	Pop.	Note	%±
1860	198		—
1870	2,512		1,168.7%
1880	4,921		95.9%
1890	7,733		57.1%
1900	9,439		22.1%
1910	8,200		−13.1%
1920	7,862		−4.1%
1930	9,527		21.2%
1940	8,714		−8.5%
1950	6,745		−22.6%
1960	5,673		−15.9%
1970	5,879		3.6%
1980	10,198		73.5%
1990	15,518		52.2%
2000	29,736		91.6%
2010	36,324		22.2%
2020	42,357		16.6%
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 42,357 people in Summit County with a population density of 22.6 people per square mile (8.7/km). Among non-Hispanic or Latino people, the racial makeup was 35,108 (82.9%) White, 163 (0.4%) African American, 67 (0.2%) Native American, 723 (1.7%) Asian, 42 (0.1%) Pacific Islander, 155 (0.4%) from other races, and 1,362 (3.2%) from two or more races. 4,737 (11.2%) people were Hispanic or Latino.

There were 21,578 (50.94%) males and 20,779 (49.06%) females, and the population distribution by age was 10,351 (24.4%) under the age of 18, 26,149 (61.7%) from 18 to 64, and 5,857 (13.8%) who were at least 65 years old. The median age was 40.8 years.

There were 15,688 households in Summit County with an average size of 2.70 of which 11,419 (72.8%) were families and 4,269 (27.2%) were non-families. Among all families, 9,553 (60.9%) were married couples, 671 (4.3%) were male householders with no spouse, and 1,195 (7.6%) were female householders with no spouse. Among all non-families, 3,171 (20.2%) were a single person living alone and 1,098 (7.0%) were two or more people living together. 5,424 (34.6%) of all households had children under the age of 18. 12,186 (77.7%) of households were owner-occupied while 3,502 (22.3%) were renter-occupied.

The median income for a Summit County household was $106,973 and the median family income was $119,592, with a per-capita income of $57,308. The median income for males that were full-time employees was $69,357 and for females $50,147. 4.5% of the population and 2.7% of families were below the poverty line.

In terms of education attainment, out of the 27,924 people in Summit County 25 years or older, 1,332 (4.8%) had not completed high school, 4,476 (16.0%) had a high school diploma or equivalency, 6,446 (23.1%) had some college or associate degree, 9,841 (35.2%) had a bachelor's degree, and 5,829 (20.9%) had a graduate or professional degree.

According to a 2000 survey by the Association of Statisticians of American Religious Bodies, Summit County is more religiously diverse than the rest of Utah. Roughly two-in-five people (44.2%) of the population claim no religion at all. 36.8% are members of the Church of Jesus Christ of Latter-day Saints (LDS Church) (compared with some 66% statewide) and 10.6% are Catholic.

Summit County was traditionally a Republican stronghold in Utah's early years. Beginning in the 1990s, it became more competitive due to the influence of Democratic-leaning Park City, with Democrats sometimes winning a plurality or majority of the countywide vote. In 1996, Bill Clinton became the first Democratic presidential nominee 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. George W. Bush carried the county in 2000 and 2004, but his performance there was worst in the state. In the 2006 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%. 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%, and Joe Biden increased her margin by 3% in 2020, solidifying the county as a safe Democratic region.

State elected offices

Position		District	Name	Affiliation	First elected
	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

United States presidential election results for Summit County, Utah

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	10,252	39.00%	15,244	57.99%	793	3.02%
2016	7,333	35.11%	10,503	50.29%	3,049	14.60%
2012	8,884	50.49%	8,072	45.87%	641	3.64%
2008	6,956	41.11%	9,532	56.34%	432	2.55%
2004	7,936	51.83%	6,977	45.57%	399	2.61%
2000	6,168	50.89%	4,601	37.96%	1,352	11.15%
1996	3,867	41.50%	4,177	44.82%	1,275	13.68%
1992	3,133	33.33%	3,013	32.06%	3,253	34.61%
1988	3,881	59.68%	2,536	39.00%	86	1.32%
1984	4,093	71.79%	1,539	27.00%	69	1.21%
1980	3,330	65.38%	1,184	23.25%	579	11.37%
1976	2,316	61.55%	1,282	34.07%	165	4.38%
1972	2,209	69.95%	836	26.47%	113	3.58%
1968	1,782	62.37%	961	33.64%	114	3.99%
1964	1,335	47.14%	1,497	52.86%	0	0.00%
1960	1,607	56.91%	1,217	43.09%	0	0.00%
1956	2,031	69.77%	880	30.23%	0	0.00%
1952	1,955	60.75%	1,263	39.25%	0	0.00%
1948	1,617	50.44%	1,556	48.53%	33	1.03%
1944	1,479	45.62%	1,761	54.32%	2	0.06%
1940	1,730	43.82%	2,215	56.10%	3	0.08%
1936	1,422	37.58%	2,344	61.95%	18	0.48%
1932	1,434	40.55%	2,028	57.35%	74	2.09%
1928	1,748	57.65%	1,260	41.56%	24	0.79%
1924	1,597	57.16%	825	29.53%	372	13.31%
1920	1,503	59.79%	874	34.77%	137	5.45%
1916	1,195	40.69%	1,495	50.90%	247	8.41%
1912	1,290	44.06%	983	33.57%	655	22.37%
1908	1,614	50.87%	1,402	44.19%	157	4.95%
1904	2,232	57.87%	1,358	35.21%	267	6.92%
1900	1,555	46.64%	1,763	52.88%	16	0.48%
1896	245	6.72%	3,402	93.28%	0	0.00%

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.

• Francis
• Henefer

• Atkinson
• Blacks Fork
• Mill City
• Wahsatch

There are three school districts covering sections of the county:

• North Summit School District
• Park City School District
• South Summit School District

Summit County also includs a local campus of Utah State University in Park City.

• List of counties in Utah
• National Register of Historic Places listings in Summit County, Utah
• Utah Transfer of Public Lands Act

• Official website