The State of Colorado is a state located in the Rocky Mountain region of the United States of America.
On February 28, 1861, outgoing U.S. President James Buchanan signed an act of Congress organizing the free Territory of Colorado. On August 1, 1876 (28 days after Centennial of the United States), U.S. President Ulysses S. Grant signed a proclamation admitting the State of Colorado to the Union as the 38th state and earning it the moniker the "Centennial State".
The state's largest city, and capital, is Denver. The Denver-Aurora-Boulder Combined Statistical Area, home to 2,927,911 people, contains more than two-thirds of the state's population. Residents of Colorado are referred to as Coloradans.
Denver has also been known historically as the Queen City of the Plains because of its important role in the agricultural industry of the plains regions along the foothills of the Colorado Front Range.