Boulder (/ˈboʊldər/) is the home rule municipality that is the county seat and the most populous municipality of Boulder County, Colorado, United States. It is the state’s 11th-most-populous municipality; Boulder is located at the base of the foothills of the Rocky Mountains at an elevation of 5,430 feet (1,655 m) above sea level. The city is 25 miles (40 km) northwest of Denver.
The city of Boulder is in Boulder Valley where the Rocky Mountains meet the Great Plains. West of the city are slabs of sedimentary stone tilted up on the foothills, known as the Flatirons. The Flatirons are a widely recognized symbol of Boulder.
The primary water flow through the city is Boulder Creek. The creek was named well ahead of the city’s founding, for all of the large granite boulders that have cascaded into the creek over the eons. It is from Boulder Creek that Boulder city is believed to have taken its name. Boulder Creek has significant water flow, derived primarily from snow melt and minor springs west of the city. The creek is a tributary of the South Platte River.
According to the United States Census Bureau, the city has a total area of 25.7 square miles (66.5 km). 24.7 square miles (63.9 km) of it is land and 1.0 square mile (2.6 km) of it (3.97%) is water.
The 40th parallel (40 degrees north latitude) runs through Boulder and can be easily recognized as Baseline Road today.
Boulder lies in a wide basin beneath Flagstaff Mountain just a few miles east of the continental divide and about 25 miles (40 km) northwest of Denver. Arapahoe Glacier provides water for the city, along with Boulder Creek, which flows through the center of the city.
Denver International Airport is located 45 miles (72 km) southeast of Boulder.
As of the 2010 census, there were 97,385 people, 41,302 households, and 16,694 families residing in the city. The population density was 3,942.7 inhabitants per square mile (1,524.0/km²). There were 43,479 housing units at an average density of 1,760.3 per square mile (680.4/km²). The racial makeup of the city was 88.0% White, 0.9% Black or African American, 0.4% Native American, 4.7% Asian, 0.1% Pacific Islander, 3.2% some other race, and 2.6% from two or more races. 8.7% of the population are Hispanic or Latino of any race.
There were 41,302 households, out of which 19.1% had children under the age of 18 living with them, 32.2% were headed by married couples living together, 5.5% had a female householder with no husband present, and 59.6% were non-families. 35.8% of all households were made up of individuals, and 7.1% were someone living alone who was 65 years of age or older. The average household size was 2.16, and the average family size was 2.84.
Boulder’s population is younger than the national average, largely due to the presence of university students. The median age at the 2010 census was 28.7 years compared to the U.S. median of 37.2 years. In Boulder, 13.9% of the residents were younger than the age of 18, 29.1% from 18 to 24, 27.6% from 25 to 44, 20.3% from 45 to 64, and 8.9% were 65 years of age or older. For every 100 females, there were 105.5 males. For every 100 females age 18 and older, there were 106.2 males.
In 2011 the estimated median household income in Boulder was $57,112, and the median family income was $113,681. Male full-time workers had a median income of $71,993 versus $47,574 for females. The per capita income for the city was $37,600. 24.8% of the population and 7.6% of families were below the poverty line. Out of the total population, 17.4% of those under the age of 18 and 6.0% of those 65 and older were living below the poverty line.
Boulder housing tends to be priced higher than surrounding areas. For the 2nd quarter of 2006, the median single-family home in Boulder sold for $548,000 and the median attached dwelling (condo or town home) sold for $262,000. According to the National Association of Realtors, during the same period the median value of one-family homes nationwide was $227,500. The median price of a home exceeded $1 million in July 2016.