BOULDER, a city of Colorado, U.S.A., on Boulder creek, just east of the continental divide, 3om. north-west of Denver, at an elevation of 5,300 ft.; the county seat of Boulder county. It is served by the Burlington, the Colorado and Southern, and the Union Pacific railways. The population in 1930 was 11,223. Protected by mountains from the winter winds, and cooled in summer by breezes from the Arapahoe, Isabel, Fair, St. Vrain, and other glaciers to the west, the average monthly mean tempera ture ranges from 32.9° F (February) to 70.I ° (August) ; and the sun shines on 328 days out of 365. The water-supply, sufficient for a population of ioo,000, comes from glacier-fed lakes ; electric energy from a large plant four miles east of the city. Extensive fields of lignite coal underlie the eastern third of the county. There are mineral springs in the vicinity of Boulder, and mines producing gold, silver, tungsten, lead, copper, and fluor-spar. The Rocky Mountain National park of 378sq.m. is not far to the north-west and the Colorado National Forest lies a few miles west. Boulder canyon and others have great scenic beauty, and the city owns 6,000ac. of mountain park-lands. Glissading on the face of the glaciers is a popular sport, and trout abound in many lakes and streams. The Colorado Chautauqua, one of the oldest and largest independent chautauquas in the country, has its per manent grounds on a beautiful site 400f t. above the city. The University of Colorado, incorporated in 1861 and opened in is in Boulder, except for its medical school, which is in Denver. It has an annual enrolment of about 3,00o besides over 3,00o in the summer session. During the summer the university maintains a camp at Arapahoe Falls. 'The stadium, seating 25,000, is built in a natural ravine on the campus.
The first settlement here was made late in 1858, and placer gold was discovered near by in 1859. The town was laid out and organized in 1859; the first city charter was secured in 1871; and a city manager form of government was adopted in 1917. Oil was struck three miles north-east of Boulder in 189i, and production reached its peak in 1903. For 12 years natural gas was supplied to the city from a single well about a mile away. For some years after 1900 most of the tungsten mined in the United States came from Nederland and Eldora, 18m. and 22m. south-west of Boulder.