Summit County is one of the 64 counties in the U.S. state of Colorado. As of the 2010 census, the population was 27,994. The county seat is Breckenridge.
According to the U.S. Census Bureau, the county has a total area of 619 square miles (1,600 km), of which 608 square miles (1,570 km) is land and 11 square miles (28 km) (1.8%) is water.
The terrain of the county is mountainous with elevations ranging from 7,957 feet (2,425 m) at Green Mountain Reservoir to 14,270 feet (4,350 m) at Grays Peak. The elevation of the county seat of Breckenridge is 9,602 feet (2,927 m), making it one the highest cities in the state of Colorado and the United States. Much of the county has an Alpine (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.
As of the census of 2000, there were 23,548 people, 9,120 households, and 4,769 families residing in the county. The population density was 39 people per square mile (15/km). There were 24,201 housing units at an average density of 40 per square mile (15/km). The racial makeup of the county was 91.84% White, 0.68% Black or African American, 0.48% Native American, 0.87% Asian, 0.07% Pacific Islander, 3.96% from other races, and 2.10% from two or more races. 9.79% of the population were Hispanic or Latino of any race.
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. 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.
The 2012 average real estate prices in Summit County were $708,660 for a single family home, $359,536 for a condo, townhome or duplex and $281,388 for a vacant piece of land (YTD through August 2012).