The City of Centennial was formed on February 7, 2001, from portions of unincorporated Arapahoe County, including the former Castlewood and Southglenn census-designated places (CDPs). The citizens of the area had voted to incorporate on September 12, 2000, choosing Centennial as the official name during the vote. The name reflects Colorado’s admission to the Union as the 38th state in 1876, the centennial year of the United States Declaration of Independence. The state of Colorado is nicknamed the “Centennial State”.
Incorporation was approved by 77% of the voters, and the population of the area at over 100,000 made it the largest incorporation in U.S. history as of its creation. The city was incorporated in large part to prevent further annexations of unincorporated areas by the city of Greenwood Village in an attempt to improve its tax base. The taxes generated from businesses in unincorporated portions of Arapahoe County funded the majority of the county’s services, including road work. A number of court cases eventually established the right of incorporation to take precedence over the right of annexation.
The city was incorporated on a promise to keep city taxes at 1%. (One of the campaigns against incorporation appealed to voters to maintain the 3.8% sales tax of the unincorporated county.) According to the City of Centennial website, the current sales tax rate is two-and-a-half times the promised rate, at 2.5%.
Since the city is relatively new, some people in the Denver-Aurora metropolitan area do not yet recognize the area by the name “Centennial”, especially since neighboring Aurora, Englewood and Littleton are the default place names assigned by the United States Postal Service for ZIP codes serving Centennial. Thus, mailing addresses designated as “Aurora”, “Englewood” or “Littleton” may actually be located in Centennial. This causes considerable confusion, as Centennial and Englewood do not even share a boundary, while some portions of Centennial are surrounded by Aurora and vice versa.
The city recently held a home rule charter convention where a new charter was adopted. The new charter was approved by voters on June 10, 2008, by a ratio of 2-to-1.
Centennial Airport, formerly Arapahoe County Airport, lies adjacent to Centennial, but is located in unincorporated Arapahoe County. The airport is not named after the city, as it predates the city by over 30 years.