Colorado is a constituent state of the United States of America. It is classified as one of the Mountain states, although only about one-half of its approximately 104,091 square miles (269,596 square kilometres) lies in the Rocky Mountains. It borders Wyoming and Nebraska on the north, Nebraska and Kansas on the east, Oklahoma and New Mexico on the south, and Utah on the west. Colorado was admitted to the Union on Aug. 1, 1876, as the 38th state. The capital is Denver.
Colorado's history is written in the names of its cities, towns, mountain ranges, and passes. Indian and Spanish names alternate with those of frontier Americans, and many ghost towns are reminders of the thousands of prospectors and homesteaders who streamed into the territory in the mid-19th century to pursue dreams of gold and grain bonanzas. The vast cattle ranges and agricultural acreage fed by huge irrigation projects are characteristic of modern Colorado, as are the diversified industries and the educational and research facilities in its urban centres.
Colorado's natural landscape ranges from the flat, grass-covered High Plains of the Great Plains, through the rolling, hilly Colorado Piedmont paralleling the Rocky Mountain front, to the high and numerous mountain ranges and plateaus that make up the southern Rocky Mountains and the Colorado Plateau. Within these areas the state rises from about 3,500 feet (1,100 metres) in the east to more than 14,000 feet in the Rockies. About 50 miles (80 kilometres) wide and 275 miles long, the Colorado Piedmont is a picturesque, hilly to mountainous landscape sandwiched between the plains and the mountains. The climate and land of the Colorado Piedmont attract tourists, homeseekers, and farmers. The major cities and the wealthy farm areas lie where the streams have broadened the valleys. Among the attractive features of the landscape is the high, grotesque, and multicoloured agglomeration of sandstones northwest of Colorado Springs known as the Garden of the Gods. In the foothills southwest of Denver is one of the world's largest and most beautiful outdoor amphitheatres, Red Rocks Park. Since 1880, more than 400 reservoirs have been built in the piedmont to store water for irrigation. These sites are meccas for water sports, hunting, and house building.
The western half of Colorado includes the huge mountain upthrust, comprising much of the southern Rocky Mountains and the Colorado Plateau, where mesas and mountain ranges alternate with broad, intervening valleys and deep, narrow canyons. With its copious amount of precipitation, this mountain land provides water for six states and Mexico. The drainage pattern from the Rockies is oriented by the mountains themselves, which form the Continental Divide, the main watershed boundary of the continent. The mountainous portion of Colorado comprises a great number of individual mountain ranges. In the north and northwest the Front, Medicine Bow, Park, and Rabbit Ears ranges are major uplifts, and Rocky Mountain National Park (established 1915) is a major attraction. The western and southwestern extremity of the state comprises the tilted and acutely uplifted layered rock of the Colorado Plateau. The Grand Mesa and the White River Plateau, both above 10,000 feet, are major attractions. The region contains several national monuments and parks, most of them primarily scenic, while Mesa Verde National Park, designated by UNESCO as a world heritage site, preserves the remnants of cliff-dwelling Indian settlements.
Location, soil, minerals, water, space for expansion, and physical beauty are positive resources in Colorado's growth. Among the Rocky Mountain states Colorado accounts for nearly two-fifths of the population but about one-half of all manufacturing employment. Although not the leader that it was in the mining bonanzas of a century ago, Colorado's mineral industry continues to make substantial contributions to the economy. Among the principal minerals are coal, petroleum, molybdenum, and sand and gravel. Northwestern Colorado has some of the largest and most valuable coal deposits in the United States, but the industry is relatively dormant because of decreasing demand. Petroleum and natural gas reserves are mostly in the form of oil shales.
Although manufacturing, agriculture, and summer tourism are the mainstays of Colorado's economy, winter sports have grown at an almost alarming rate. Transport, housing, and lift facilities are continually expanding to meet the annual ski invasion. Fear of enemy attack on both U.S. coasts during World War II stimulated the development of government facilities in Colorado because of its interior, yet accessible, location. The Denver Federal Center, Rocky Mountain Arsenal, Camp (later Fort) Carson, Camp Hale, and other installations brought thousands of newcomers to the state. After the war many of these newcomers stayed on to develop ski resorts, the electronics industry, and the U.S. Air Force Academy. By the 1980s, some three-fifths of the state's population had been born outside of Colorado. Tourism replaced mining and agriculture as the mainstay of the economy, while official state policy promoted orderly growth of the economy and the infrastructure to support it.
Colorado has a well-developed transportation system and ranks first among the mountain states in road mileage. Main highways tend to be east–west, circumvent high mountain masses, and follow valleys and canyons to their heads in the 32 mountain passes over the Continental Divide. The highest of the passes, at 12,183 feet (3,713 metres), is on the seasonal Trail Ridge Road in Rocky Mountain National Park. A number of other passes exceed 10,000 feet in elevation. One of the nation's major east–west interstate highways runs through the state, utilizing twin vehicular tunnels under the Continental Divide west of Denver. The Denver International Airport (opened 1995) is a major centre in the nation's air traffic pattern. The facility, which covers 53 square miles (138 square kilometres), is served by several major airlines, and carriers also link Denver with other Colorado cities and with neighbouring states. Railroad lines in Colorado are mainly bulk-freight carriers using multilevel railcars and flatcars for containerized freight, although a main east–west Amtrak passenger route passes through Denver and the Rockies.
