Summit County, Colorado

{{short description|County in Colorado, United States}} {{For|other counties with similar names|Summit County (disambiguation){{!}}Summit County}} {{Use mdy dates|date=January 2026}} {{Use American English|date=January 2026}} {{infobox U.S. county | county = Summit County | state = Colorado | ex image = Summit County court house in Colorado.jpg | ex image size = 300px | ex image cap = The Summit County Courthouse in Breckenridge | type = County | flag = | seal = Seal of Summit County, Colorado.png | logo =  | coordinates = {{Coord|39.621023|-106.137555|region:US-CO_type:county|display=inline,title}} | founded = November 1, 1861 | named for = Continental Divide | seat wl = Breckenridge | largest city wl = Silverthorne | city type = town | leader type = | leader_name = | area_total_sq_mi = 619.259 | area_land_sq_mi = 608.328 | area_water_sq_mi = 10.931 | area percentage = 1.77% | population_as_of = 2020 | population_total = 31055 | pop_est_as_of = 2025 | population_est = 31517 {{increase}} | density_sq_mi = auto | time zone = Mountain | area codes = 970 and 748 | district = 2nd | website = {{URL|https://www.summitcountyco.gov/|summitcountyco.gov}} | footnotes = }}

'''Summit County''' is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 31,055,<ref name="2020 Census (City)">{{cite web|title=Explore Census Data |url=https://data.census.gov/profile/Summit_County,_Colorado?g=050XX00US08117 |publisher=United States Census Bureau |access-date=November 29, 2025}}</ref> and was estimated to be 30,882 in 2024.<ref name="QF"/> The county seat is Breckenridge.<ref name="NACo">{{cite web|title=Find a County |url=https://ce.naco.org/?find=true |publisher=National Association of Counties |access-date=November 29, 2025}}</ref> Summit County comprises the Breckenridge, CO Micropolitan Statistical Area.<ref name=OMB_10-02>{{cite web|title=OMB Bulletin No. 10-02: Update of Statistical Area Definitions and Guidance on Their Uses |url=https://obamawhitehouse.archives.gov/sites/default/files/omb/assets/bulletins/b10-02.pdf |date=December 1, 2009 |access-date=April 19, 2012 |url-status=live |archive-url=https://web.archive.org/web/20170121004722/https://obamawhitehouse.archives.gov/sites/default/files/omb/assets/bulletins/b10-02.pdf |via=National Archives |work=Office of Management and Budget |archive-date=January 21, 2017}}</ref><ref>See the Colorado census statistical areas.</ref>

==History== Summit County was organized as one of the seventeen original Colorado counties by the First Territorial Legislature on November 1, 1861. It was named for the many mountain summits in the county. Until February 2, 1874, its boundaries included the area now comprising Summit County, Grand County, Routt County, Moffat County, Garfield County, Eagle County, and Rio Blanco County.

In 1874, the northern half of the original Summit County was split off to form Grand County; with the creation of Garfield and Eagle counties in 1883, Summit County arrived at its present boundaries. In addition, Summit County has seen two major boom eras.

==Geography== According to the United States Census Bureau, the county has a total area of {{convert|619.259|sqmi}}, of which {{convert|608.328|sqmi}} is land and {{convert|10.931|sqmi}} (1.77%) is water.<ref>{{Cite web|title=2025 County Gazetteer Files – Colorado |url=https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2025_Gazetteer/2025_gaz_counties_08.txt |publisher=United States Census Bureau |access-date=November 29, 2025}}</ref> It is the 55th largest county in Colorado by total area.<ref>{{Cite web|title=U.S. Census Bureau QuickFacts: Summit County, Colorado |url=https://www.census.gov/quickfacts/geo/chart/summitcountycolorado/LND110220 |website=www.census.gov |access-date=November 29, 2025 |language=en}}</ref>

The terrain of the county is mountainous with elevations ranging from {{convert|7957|ft|m}} at Green Mountain Reservoir to {{convert|14270|ft|m}} at Grays Peak. The elevation of the county seat of Breckenridge is {{convert|9602|ft|m}}, making it one of the highest cities in the state of Colorado and the United States.<ref>"Elevation distribution for all U.S. cities," http://www.city-data.com/top13.html, accessed August 2, 2017</ref> Much of the county has an alpine climate (ET in the Köppen Classification) characterized by tundra vegetation. Breckenridge and other similar elevations in the county have a subarctic climate (Dfc) characterized by cool summers and abundant snowfall in winter.

===Adjacent counties=== * Grand County – north * Clear Creek County – east * Park County – southeast * Lake County – southwest * Eagle County – west

===Major highways=== * 20px Interstate 70 * {{jct|state=CO|BL|70|dab1=Frisco}} * 20px U.S. Highway 6 * 20px State Highway 9 * 20px State Highway 91

==Demographics== {{US Census population | 1870 = 258 | 1880 = 5459 | 1890 = 1906 | 1900 = 2744 | 1910 = 2003 | 1920 = 1724 | 1930 = 987 | 1940 = 1754 | 1950 = 1135 | 1960 = 2073 | 1970 = 2665 | 1980 = 8848 | 1990 = 12281 | 2000 = 23548 | 2010 = 27994 | 2020 = 31055 | estyear = 2025 | estimate = 31517 | estref = <ref name="USCensusEst2025">{{cite web|title=County Population Totals and Components of Change: 2020-2025 |url=https://www.census.gov/data/tables/time-series/demo/popest/2020s-counties-total.html |access-date=April 10, 2026}}</ref> {{increase}} | align-fn = center | footnote = U.S. Decennial Census<ref>{{cite web|title=U.S. Decennial Census |url=https://www.census.gov/programs-surveys/decennial-census.html |publisher=United States Census Bureau |access-date=June 11, 2014}}</ref> 1790–1960<ref>{{cite web|title=Historical Census Browser |url=http://mapserver.lib.virginia.edu |publisher=University of Virginia Library |url-status=live |date=2007 |access-date=June 11, 2014 |archive-url=https://web.archive.org/web/20091212224028/http://mapserver.lib.virginia.edu/ |archive-date=December 12, 2009}}</ref> 1900–1990<ref>{{cite web|last=Forstall |first=Richard L. |title=Population of Counties by Decennial Census: 1900 to 1990 |url=https://www.census.gov/population/cencounts/co190090.txt |publisher=United States Census Bureau |url-status=live |date=March 27, 1995 |access-date=June 11, 2014 |archive-url=https://web.archive.org/web/19990219135447/http://www.census.gov/population/cencounts/co190090.txt |archive-date=February 19, 1999}}</ref> 1990–2000<ref>{{cite web|title=Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000 |url=https://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |url-status=live |publisher=United States Census Bureau |access-date=June 11, 2014 |archive-url=https://web.archive.org/web/20100327165705/http://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |archive-date=March 27, 2010}}</ref> 2010–2020<ref name="QF">{{Cite web|title=U.S. Census Bureau QuickFacts: Summit County, Colorado |url=https://www.census.gov/quickfacts/fact/table/summitcountycolorado/PST045224 |access-date=November 29, 2025 |website=www.census.gov |language=en}}</ref> | align = right }}

===2020 census===

As of the 2020 census, the county had a population of 31,055. Of the residents, 16.8% were under the age of 18 and 13.0% were 65 years of age or older; the median age was 38.1 years. For every 100 females there were 119.5 males, and for every 100 females age 18 and over there were 120.7 males. 83.9% of residents lived in urban areas and 16.1% lived in rural areas.<ref name="Census2020DHC">{{cite web|title=2020 Decennial Census Demographic and Housing Characteristics (DHC)|url=https://api.census.gov/data/2020/dec/dhc?get=NAME%2CP2_002N%2CP2_003N&for=county%3A117&in=state%3A08|website=United States Census Bureau|year=2023|access-date=2025-12-08|df=mdy}}</ref><ref name="Census2020DP">{{cite web|title=2020 Decennial Census Demographic Profile (DP1)|url=https://api.census.gov/data/2020/dec/dp?get=NAME%2CDP1_0021P%2CDP1_0024P%2CDP1_0025C%2CDP1_0049C%2CDP1_0045C%2CDP1_0069C%2CDP1_0073C%2CDP1_0125P%2CDP1_0126P%2CDP1_0129P%2CDP1_0138P%2CDP1_0139P%2CDP1_0141P%2CDP1_0142P%2CDP1_0143P%2CDP1_0145P%2CDP1_0146P%2CDP1_0147C%2CDP1_0148C%2CDP1_0149C%2CDP1_0156C%2CDP1_0157C%2CDP1_0158C%2CDP1_0159P%2CDP1_0160P&for=county%3A117&in=state%3A08|website=United States Census Bureau|year=2021|access-date=2025-12-08|df=mdy}}</ref><ref name="Census2020PL">{{cite web|title=2020 Decennial Census Redistricting Data (Public Law 94-171)|url=https://api.census.gov/data/2020/dec/pl?get=NAME%2CP1_001N%2CP1_003N%2CP1_004N%2CP1_005N%2CP1_006N%2CP1_007N%2CP1_008N%2CP1_009N%2CP2_001N%2CP2_002N%2CH1_001N%2CH1_002N&for=county%3A117&in=state%3A08|website=United States Census Bureau|year=2021|access-date=2025-12-08|df=mdy}}</ref>

{| class="wikitable" style="text-align:center;" |+'''Summit County, Colorado – Racial and ethnic composition''' {{nobold|''Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.''}} !Race / Ethnicity (''NH = Non-Hispanic'') !Pop 2000<ref name=2000CensusP004>{{Cite web|title=P004: Hispanic or Latino, and Not Hispanic or Latino by Race – 2000: DEC Summary File 1 – Summit County, Colorado|url=https://data.census.gov/table/DECENNIALSF12000.P004?q=P004:+HISPANIC+OR+LATINO,+AND+NOT+HISPANIC+OR+LATINO+BY+RACE+[73]&g=050XX00US08117|publisher=United States Census Bureau |access-date=February 7, 2026|df=mdy }}</ref> !Pop 2010<ref name=2010CensusP2>{{Cite web|title=P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2010: DEC Redistricting Data (PL 94-171) - Summit County, Colorado|url=https://data.census.gov/table/DECENNIALPL2010.P2?q=p2&g=050XX00US08117|website=United States Census Bureau |access-date=February 7, 2026|df=mdy }}</ref> !{{partial|Pop 2020}}<ref name=2020CensusP2>{{Cite web|title=P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) - Summit County, Colorado|url=https://data.census.gov/table/DECENNIALPL2020.P2?q=p2&g=050XX00US08117|website=United States Census Bureau |access-date=February 7, 2026|df=mdy }}</ref> !% 2000 !% 2010 !{{partial|% 2020}} |- |White alone (NH) |20,411 |23,158 |style='background: #ffffe6; |23,782 |86.68% |82.72% |style='background: #ffffe6; |76.58% |- |Black or African American alone (NH) |157 |208 |style='background: #ffffe6; |232 |0.67% |0.74% |style='background: #ffffe6; |0.75% |- |Native American or Alaska Native alone (NH) |85 |55 |style='background: #ffffe6; |67 |0.36% |0.20% |style='background: #ffffe6; |0.22% |- |Asian alone (NH) |201 |269 |style='background: #ffffe6; |407 |0.85% |0.96% |style='background: #ffffe6; |1.31% |- |Pacific Islander alone (NH) |16 |13 |style='background: #ffffe6; |20 |0.07% |0.05% |style='background: #ffffe6; |0.06% |- |Other race alone (NH) |18 |31 |style='background: #ffffe6; |150 |0.08% |0.11% |style='background: #ffffe6; |0.48% |- |Mixed race or Multiracial (NH) |354 |271 |style='background: #ffffe6; |1,062 |1.50% |0.97% |style='background: #ffffe6; |3.42% |- |Hispanic or Latino (any race) |2,306 |3,989 |style='background: #ffffe6; |5,335 |9.79% |14.25% |style='background: #ffffe6; |17.18% |- |'''Total''' |'''23,548''' |'''27,994''' |style='background: #ffffe6; |'''31,055''' |'''100.00%''' |'''100.00%''' |style='background: #ffffe6; |'''100.00%''' |}

The racial makeup of the county was 79.7% White, 0.8% Black or African American, 0.8% American Indian and Alaska Native, 1.3% Asian, 0.1% Native Hawaiian and Pacific Islander, 8.8% from some other race, and 8.5% from two or more races. Hispanic or Latino residents of any race comprised 17.2% of the population.<ref name="Census2020PL"/>

There were 12,939 households in the county, of which 24.8% had children under the age of 18 living with them and 18.0% had a female householder with no spouse or partner present. About 26.5% of all households were made up of individuals and 6.6% had someone living alone who was 65 years of age or older.<ref name="Census2020DP"/>

There were 31,342 housing units, of which 58.7% were vacant. Among occupied housing units, 63.9% were owner-occupied and 36.1% were renter-occupied. The homeowner vacancy rate was 1.9% and the rental vacancy rate was 26.6%.<ref name="Census2020DP"/>

===2000 census=== As of the 2000 census, there were 23,548 people, 9,120 households, and 4,769 families residing in the county. The population density was {{convert|39.0|PD/sqmi|PD/km2|1}}. There were 24,201 housing units at an average density of {{convert|40.0|/sqmi|/km2|1}}. The racial makeup of the county was 91.84% White, 0.68% African American, 0.48% Native American, 0.87% Asian, 0.07% Pacific Islander, 3.96% from some other races and 2.10% from two or more races. Hispanic or Latino people of any race were 9.79% of the population.

There were 9,120 households, out of which 24.00% had children under the age of 18 living with them, 44.00% were married couples living together, 4.40% had a female householder with no husband present, and 47.70% were non-families. 21.60% of all households were made up of individuals, and 1.60% had someone living alone who was 65 years of age or older. The average household size was 2.48 and the average family size was 2.86.

In the county, the population was spread out, with 17.40% under the age of 18, 15.70% from 18 to 24, 44.30% from 25 to 44, 19.40% from 45 to 64, and 3.30% who were 65 years of age or older. The median age was 31 years. As of 2014, the life expectancy in Summit County was 86.83 years, the longest average life expectancy of any county in the United States.<ref name="IHME">{{cite web|title=US Health Map |url=https://vizhub.healthdata.org/subnational/usa |website=Institute for Health Metrics and Evaluation |publisher=University of Washington |access-date=May 8, 2017}}</ref> For every 100 females there were 139.00 males. For every 100 females age 18 and over, there were 144.90 males.

The median income for a household in the county was $56,587, and the median income for a family was $66,914 (these figures had risen to $65,281 and $80,441 respectively as of a 2007 estimate). Males had a median income of $33,741 versus $27,017 for females. The per capita income for the county was $28,676. About 3.10% of families and 9.00% of the population were below the poverty line, including 4.30% of those under age 18 and 3.40% of those age 65 or over. [[Image:Reservoir in the Rocky Mountains.jpg|thumb|upright|Snowmelt runoff fills Lake Dillon in Summit County]]

==Life expectancy== According to a report in the Journal of the American Medical Association, residents of Summit County had a 2014 life expectancy from birth of 86.83 years in 2014, the longest in the United States.<ref>{{Cite journal|last=Dwyer-Lindgren |first=Laura |title=Inequalities in Life Expectancy Among US Counties, 1980 to 2014 |url=https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2626194 |journal=JAMA Internal Medicine |doi=10.1001/jamainternmed.2017.0918 |pmc=5543324 |pmid=28492829 |volume=177 |issue=7 |pages=1003–1011 |date=May 8, 2017}}</ref> Both men and women live longer in Summit County than in any other county in the United States: 85.5 years for men and 88.0 years for women is the life expectancy at birth.<ref>"County Profile: Summit County Colorado," http://www.healthdata.org/sites/default/files/files/county_profiles/US/2015/County_Report_Summit_County_Colorado.pdf, accessed August 2, 2017</ref> Two contiguous counties, Pitkin and Eagle Counties, rank numbers two and three in the nation in life expectancy. Factors contributing to the high life expectancy in Summit County are "high education, high income, high access to medical care, the people are physically active, obesity is lower than anywhere else — so you’re doing it right,” said Dr. Ali Mokdad, one of the study's co-authors.<ref>Achenbach, Joel, "U.S. life expectancy varies more than 20 years from county to county," ''Washington Post'', May 8, 2017</ref>

==Education== ===K��12 schools=== ====Elementary schools==== * Breckenridge Elementary School * Dillon Valley Elementary School (Dillon) * Frisco Elementary School * Silverthorne Elementary School * Summit Cove Elementary School (Dillon) * Upper Blue Elementary School (Breckenridge)

====Middle school==== * Summit Middle School (Frisco)

====High schools==== * Snowy Peaks Junior/Senior High School (Frisco) * Summit High School (between Frisco and Breckenridge)

===Higher education=== Colorado Mountain College operates campuses in Breckenridge and Dillon.

==Politics== Summit County is liberal in most elections. Since 1988 the county has trended strongly toward the Democratic Party, like many other counties in Colorado dominated by ski towns. In 2020, Joe Biden's performance was the best by a Democrat since 1916, and Kamala Harris' performance was only slightly worse in 2024.

{{PresHead|place=Summit County, Colorado|source=<ref>{{cite web|last=Leip |first=David |title=Dave Leip's Atlas of U.S. Presidential Elections |url=http://uselectionatlas.org/RESULTS/ |website=uselectionatlas.org |access-date=May 26, 2017}}</ref>}}  {{PresRow|1880|Democratic|1,289|1,328|24|Colorado}} {{PresRow|1884|Republican|609|556|8|Colorado}} {{PresRow|1888|Republican|701|557|2|Colorado}} {{PresRow|1892|Populist|279|0|811|Colorado}} {{PresRow|1896|Democratic|28|1,243|2|Colorado}} {{PresRow|1900|Democratic|394|967|17|Colorado}} {{PresRow|1904|Democratic|561|569|35|Colorado}} {{PresRow|1908|Democratic|366|743|35|Colorado}} {{PresRow|1912|Democratic|179|600|186|Colorado}} {{PresRow|1916|Democratic|268|717|35|Colorado}} {{PresRow|1920|Republican|418|388|24|Colorado}} {{PresRow|1924|Republican|354|241|150|Colorado}} {{PresRow|1928|Republican|362|306|13|Colorado}} {{PresRow|1932|Democratic|224|397|23|Colorado}} {{PresRow|1936|Democratic|268|496|5|Colorado}} {{PresRow|1940|Democratic|479|540|5|Colorado}} {{PresRow|1944|Republican|326|237|3|Colorado}} {{PresRow|1948|Democratic|292|378|5|Colorado}} {{PresRow|1952|Republican|442|271|1|Colorado}} {{PresRow|1956|Republican|429|235|0|Colorado}} {{PresRow|1960|Republican|424|400|3|Colorado}} {{PresRow|1964|Democratic|344|483|1|Colorado}} {{PresRow|1968|Republican|536|301|97|Colorado}} {{PresRow|1972|Republican|1,082|707|44|Colorado}} {{PresRow|1976|Republican|1,826|1,087|227|Colorado}} {{PresRow|1980|Republican|2,027|1,285|1,043|Colorado}} {{PresRow|1984|Republican|3,253|1,588|77|Colorado}} {{PresRow|1988|Republican|2,893|2,595|136|Colorado}} {{PresRow|1992|Democratic|2,256|3,344|2,770|Colorado}} {{PresRow|1996|Democratic|3,261|3,970|1,188|Colorado}} {{PresRow|2000|Democratic|4,497|5,304|1,267|Colorado}} {{PresRow|2004|Democratic|5,370|8,144|221|Colorado}} {{PresRow|2008|Democratic|4,883|9,802|214|Colorado}} {{PresRow|2012|Democratic|5,571|9,347|394|Colorado}} {{PresRow|2016|Democratic|5,100|9,557|1,517|Colorado}} {{PresRow|2020|Democratic|5,322|12,631|526|Colorado}} {{PresRow|2024|Democratic|5,244|11,762|539|Colorado}} {{PresFoot}} {{U.S. SenHead|place=Summit County, Colorado|Seat=2|source=}}  {{U.S. SenRow|2020|Democratic|5,817|12,175|415|Colorado}} {{U.S. SenFoot}} {{U.S. SenHead|place=Summit County, Colorado|Seat=3|source=}}  {{U.S. SenRow|2022|Democratic|4,211|9,710|322|Colorado}} {{U.S. SenFoot}} {{C.O. GovHead|place=Summit County|Seat=|source=}}  {{C.O. GovRow|2022|Democratic|3,650|10,383|243}} {{C.O. GovFoot}}

==Communities== ===Towns=== * Blue River * Breckenridge * Dillon * Frisco * Keystone * Montezuma * Silverthorne

===Census-designated places=== * Copper Mountain * Heeney

===Ghost towns=== * Dyersville * Kokomo * Parkville * Preston * Saints John * Tiger

==Recreation== ===National protected areas=== * White River National Forest * Eagles Nest Wilderness

===Ski areas=== * Arapahoe Basin * Breckenridge * Copper Mountain * Keystone

===Trails and byways=== * American Discovery Trail * Colorado Trail * Continental Divide National Scenic Trail * Great Parks Bicycle Route * Top of the Rockies National Scenic Byway * TransAmerica Trail Bicycle Route * Vail Pass National Recreation Trail * Wheeler Ten Mile National Recreation Trail

===Lakes=== The county has three reservoirs, Lake Dillon, Green Mountain Reservoir, and Clinton Gulch Dam Reservoir that are also popular recreation sites. {{Clear}}

===Islands=== * Silver Dollar Island

===Concert venues=== * Dillon Amphitheater {{clear}}

==References== thumb|upright|Gold specimen from the Breckenridge Mining District {{reflist}}

==External links== {{sister project links|auto=yes}} * [https://www.colorado.gov/ State of Colorado] ** [https://www.historycolorado.org/ History Colorado] * {{Official website|https://www.summitcountyco.gov/}} * [https://web.archive.org/web/20070205102713/http://www.stanwyck.com/cogenweb/cocounties.html Colorado County Evolution by Don Stanwyck] * [http://www.ghosttowns.com/states/co/kokomo.html Kokomo and Racen ghost towns]

{{Summit County, Colorado|collapse_state=expanded}} {{Geographic Location |Centre = Summit County, Colorado |North = Grand County |Northeast = |East = Clear Creek County |Southeast = Park County |South = |Southwest = Lake County |West = Eagle County |Northwest = }} {{Colorado}} {{authority control}}

Category:Summit County, Colorado Category:Colorado counties Category:1861 establishments in Colorado Territory Category:Colorado Western Slope Category:Populated places in the United States established in 1861 Category:Rocky Mountains of Colorado