Archaeological evidence shows that Boulder Valley has been continuously inhabited by Native American tribes for over 13,000 years, beginning in the late Pleistocene era.

Throughout the Paleo-Indian, Archaic, and Late Prehistoric periods, Indigenous peoples moved seasonally between the mountains and plains, taking shelter in winter along the Front Range trough where Boulder now lies.

[12] The Indigenous Nations who have ties to the Boulder Valley include the Apache, Arapaho, Cheyenne, Comanche, Kiowa, Pawnee, Shoshone, Sioux, and Ute peoples.

Hoping to preserve residents' views of the mountains, in 1972, the city enacted an ordinance limiting the height of newly constructed buildings.

The Flatirons, slabs of sedimentary stone tilted up on the foothills, are located west of the city and are a widely recognized symbol of Boulder.

[citation needed] Boulder Creek has significant water flow, derived primarily from snow melt and minor springs west of the city.

However, with the threat of West Nile virus, the city began an integrative plan[34] to control the mosquito population in 2003 that includes chemical pesticides.

Because of orographic lift, the mountains to the west often dry out the air passing over the Front Range, shielding the city from precipitation in winter, though heavy snowfalls may occur.

Due to the high elevation, a strong warming sun can quickly melt snow cover during the day and Chinook winds bring rapid warm-ups throughout the winter months.

Under Artistic Director Kenneth Woods, The Colorado MahlerFest Orchestra draws together young professionals, conservatory and university students, and advanced amateurs.

[68][69] Beginning in 1983, hundreds of people head to the Boulder Reservoir on New Year's Day to take part in the annual polar bear plunge.

[citation needed] Starting in 1998, dozens of people have taken part in a Halloween run down the city's streets wearing only shoes and a hollowed-out pumpkin on their heads.

[72] For several years on April 20, thousands of people gathered on the CU Boulder campus to celebrate 420 and smoke marijuana at and before 4:20 pm.

[citation needed] The 2010 head count was officially between 8,000 and 15,000 with some discrepancy between the local papers and the university administrators, who have been thought to have been attempting to downplay the event.

[citation needed] Some enthusiasts gather wearing costumes and decorating their bikes; themes are an integral part of the cruiser tradition.

[79] Returning to an underground format, where enthusiasts must become part of the social network before gaining access to event sites, the Boulder Cruiser Ride has continued as a local tradition.

[citation needed] On May 30, 2013, over 400 riders attended the Thursday-night Cruiser Ride in honor of "Big Boy", an elk that was shot and killed on New Year's Day by an on-duty[80] Boulder Police officer.

The city operates public service Boulder 8 TV on cable (high- and standard-definition), which airs, live-streams and archives council meetings.

KRKS-FM 94.7, owned and operated by Salem Media Group and affiliated with SRN News, offers a Christian talk and teaching format, and has its transmitter located on Lee Hill, northwest of Boulder.

Considerable road traffic enters the city each morning and leaves each afternoon, since many employees live in Longmont, Lafayette, Louisville, Broomfield, Westminster, and Denver.

Boulder provides a community transit network that connects downtown, the University of Colorado campuses, and local shopping amenities.

Due in part to these investments in pedestrian, bicycle, and transit infrastructure, Boulder has been recognized both nationally and internationally for its transportation system.

[107] In 2009, the Boulder metropolitan statistical area (MSA) ranked as the fourth highest in the United States for percentage of commuters who biked to work, at 5.4 percent.

[108] In 2013, the Boulder MSA ranked as the fourth lowest in the United States for percentage of workers who commuted by private automobile, at 71.9 percent.

The HOP, SKIP, JUMP, Bound, DASH and Stampede routes run throughout the city and connect to nearby communities with departures every ten minutes during peak hours, Monday-Friday.

Front Range Passenger Rail is a current proposal (as of 2023) to link the cities from Pueblo in the south, north to Fort Collins and possibly to Cheyenne, Wyoming.

Boulder, well known for its bicycle culture, has hundreds of miles of bicycle-pedestrian paths, lanes, and routes that interconnect to create a renowned network of bikeways usable year-round.

[124] In the American version of the television sitcom The Office, the character Michael Scott leaves the show in season 7 and moves with his fiancée to Boulder.

It has served as something of a signature tune for the artist and recounts her feelings of grief in the years following the death of country rock star and mentor Gram Parsons.

[126] The Comedy Central television show Broad City ends with the protagonist, Abby, moving to Boulder for an art fellowship.