The City and County of Denver (; Arapaho: Niinéniiniicíihéhe') is the largest city and the capital of the U.S. state of Colorado. Denver is also the second most populous county in Colorado after El Paso County. Denver is a consolidated city and county located in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains. The Denver downtown district is located immediately east of the confluence of Cherry Creek with the South Platte River, approximately east of the foothills of the Rocky Mountains. Denver is nicknamed the Mile-High City because its official elevation is exactly one mile or above sea level, making it one of the highest major cities in the United States. The 105th meridian west of Greenwich passes through Union Station and is the temporal reference for the Mountain Time Zone.
The 2011 estimated population of Denver was 619,968 which ranks it as the 23rd most populous U.S. city. The 10-county Denver-Aurora-Broomfield, CO Metropolitan Statistical Area had an estimated 2011 population of 2,599,504 and ranked as the 21st most populous U.S. metropolitan statistical area. The 12-county Denver-Aurora-Boulder Combined Statistical Area had an estimated 2011 population of 3,157,520, which ranks as the 16th most populous U.S. metropolitan area. Denver is the center and the most populous city of the Front Range Urban Corridor, an oblong urban region stretching across 18 counties in two states with an estimated 2011 population of 4,423,936. Denver is the most populous city within a radius and the second most populous city in the Mountain West and the Southwestern United States after Phoenix, Arizona.
Denver City was founded in November 1858 as a mining town during the Pikes Peak Gold Rush in western Kansas Territory. That summer, a group of gold prospectors from Lawrence, Kansas, arrived and established Montana City on the banks of the South Platte River. This was the first settlement in what was later to become the city of Denver. The site faded quickly, however, and by the summer of 1859 it was abandoned in favor of Auraria (named after the gold mining town of Auraria, Georgia), and St. Charles City.
Finally linked to the rest of the nation by rail, Denver prospered as a service and supply center. The young city grew during these years, attracting millionaires with their mansions, as well as the poverty and crime of a rapidly growing city. Denver citizens were proud when the rich chose Denver and were thrilled that Horace Tabor, the Leadville mining millionaire, built an impressive business block at 16th and Larimer as well as the elegant Tabor Grand Opera House. Luxurious hotels, including the much-loved Brown Palace Hotel, soon followed, as well as splendid homes for millionaires like the Croke, Patterson, Campbell Mansion at 11th and Pennsylvania and the now-demolished Moffat Mansion at 8th and Grant. Intent on transforming Denver into one of the world's great cities, leaders wooed industry and enticed laborers to work in these factories. Soon, in addition to the elite and a large middle class, Denver had a growing population of German, Italian, and Chinese laborers, soon followed by African-Americans and Spanish-surname workers. Unprepared for this influx, the Silver Crash of 1893 unsettled political, social, and economic balances, laying the foundation for ethnic bigotry, such as the Red Scare and the rise of the Ku Klux Klan, as well as corruption and crime.
Between 1880 and 1895 the city experienced a huge rise in corruption, as crime bosses, such as Soapy Smith, worked side by side with elected officials and the police to control elections, gambling, and the bunko gangs. The city also experienced a depression in 1893 after the crash of silver prices. In 1887, the precursor to the international charity United Way was formed in Denver by local religious leaders who raised funds and coordinated various charities to help Denver's poor. By 1890, Denver had grown to be the second-largest city west of Omaha, Nebraska, but by 1900 it had dropped to third place behind San Francisco and Los Angeles. In 1900, whites represented 96.8% of Denver's population.
In 1901, the Colorado General Assembly voted to split Arapahoe County into three parts: a new consolidated City and County of Denver, a new Adams County, and the remainder of the Arapahoe County to be renamed South Arapahoe County. A ruling by the Colorado Supreme Court, subsequent legislation, and a referendum delayed the creation of the City and County of Denver until November 15, 1902.
Denver has hosted the Democratic National Convention twice, during the years of 1908, and again in 2008, taking the opportunity to promote the city's status on the national, political, and socioeconomic stage.
From 1953 to 1989, the Rocky Flats Plant, a DOE nuclear weapon facility formerly located about 15 miles from Denver, produced fissile plutonium "pits" for nuclear warheads. A major fire at the facility in 1957, as well as leakage from nuclear waste stored at the site between 1958 and 1968, resulted in the contamination of some parts of Denver, to varying degrees, with plutonium-239, a harmful radioactive substance with a half-life of 24,200 years. A study by the Jefferson County health director, Dr. Carl Johnson, in 1981 linked the contamination to an increase in birth defects and cancer incidence in central Denver and nearer Rocky Flats. Later studies confirmed many of his findings. Plutonium contamination was still present outside the former plant site , and presents risks to building the envisioned Jefferson Parkway, which would complete Denver's automotive beltway.
Denver was selected in 1970 to host the 1976 Winter Olympics to coincide with Colorado's centennial celebration, but in November 1972 Colorado voters struck down ballot initiatives allocating public funds to pay for the high costs of the games, which were subsequently moved to Innsbruck, Austria. The notoriety of becoming the only city ever to decline to host an Olympiad after being selected has made subsequent bids difficult. The movement against hosting the games was based largely on environmental issues and was led by State Representative Richard Lamm, who was subsequently elected to three terms (1975–87) as Colorado governor. Denver explored a potential bid for the 2022 Winter Olympics, but no bid will be submitted. In 2010, Denver adopted a comprehensive update of its zoning code. The new zoning was developed to guide development as envisioned in adopted plans such as Blueprint Denver, Transit Oriented Development Strategic Plan, Greenprint Denver, and the Strategic Transportation Plan.
Denver has also been known historically as the Queen City of the Plains and the Queen City of the West, because of its important role in the agricultural industry of the high-plains region in eastern Colorado and along the foothills of the Colorado Front Range. Several US Navy ships have been named USS Denver in honor of the city.