Boulder County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 330,758. The most populous municipality in the county and the county seat is Boulder. Boulder County comprises the Boulder, Colorado Metropolitan Statistical Area, which is included in the 12-county Denver-Aurora-Greeley, CO Combined Statistical Area.
History
Boulder County was one of the original 17 counties created by the Territory of Colorado on November 1, 1861. The county was named for Boulder City and Boulder Creek, so named because of the abundance of boulders in the creek which hampered early gold prospecting efforts. Boulder County retains essentially the same borders as in 1861, although a of its southeastern corner and its approximate population of 40,000 became part of the City and County of Broomfield in 2001.
Before the arrival of the first US settlers, the area was occupied by Native Americans led by Chief Niwot on the plains and seasonally by Utes in the mountains to the west. The first European American settlers were gold prospectors led by Captain Thomas Aikins. His group of about twenty settled at the mouth of Boulder Creek Canyon on October 17, 1858. Chief Niwot told them not to stay and it is said they promised to move into the mountains to prospect in the spring. However, in February 1859, they founded the town of Boulder. At about the same time, they also founded the first Gold Mining town in what would become Colorado, Gold Hill which is about 10 miles west from Boulder. Gold Hill was founded because of the placer gold discovered there. The area was the site of the first commercial scale placer mine in Colorado, producing over 5,500 ounces of gold in the first year of operations (1859).
In late December 2021, the Marshall Fire raged through the parched lands near Boulder, Colorado. Marshall Fire is the most destructive in Colorado's history. The fire impacted City of Superior, City of Louisville and unincorporated Boulder County areas. 991 homes were destroyed with an additional 127 damaged. Over 13,000 people in Superior and 21,000 in Louisville were ultimately evacuated while the fire was spreading due to unusual 100 mile per hour winds. Additionally, one person died and another is missing and presumed dead. The cause of the fire has not been officially announced, pending an investigation. However, an incident report filed by a ranger with Boulder Open Space and Mountain Parks identified two ignition points for the fire. The first ignition point was a shed that began to burn at approximately 11:30AM MST, December 30, 2021. The second ignition point was upwind from the first, and started around noon of the same day on "western side of the Marshall Mesa trailhead".
Geography
thumb|upright=1.3|View of the eastern and southern borders of Boulder County and adjacent areas in Weld, Broomfield, and Jefferson counties, with north oriented to the left. The city of Boulder is near the lower border. Taken from the International Space Station on July 1, 2022.
According to the U.S. Census Bureau, the county has a total area of , of which is land and (1.9%) is water.
Adjacent counties
Major highways
- 20px U.S. Highway 36 (Denver-Boulder Turnpike)
- 20px U.S. Highway 287
- 20px State Highway 7
- 20px State Highway 42
- 20px State Highway 52
- 20px State Highway 66
- 20px State Highway 72
- 20px State Highway 93
- 20px State Highway 119
- 20px State Highway 170
- Northwest Parkway (tollway)
National protected areas
Rocky Mountain National Park is in Boulder County, Larimer County, and Grand County. Longs Peak, the park's highest summit at elevation, is located in Boulder County.
State protected area
- Eldorado Canyon State Park
Scenic trails and byways
- Continental Divide National Scenic Trail
- Peak to Peak Scenic and Historic Byway
Historic district
- Colorado Chautauqua National Historic District