High Quality Content by WIKIPEDIA articles! The Denver-Aurora-Boulder, CO Combined Statistical Area is a United States Census Bureau defined Combined Statistical Area (CSA) located in the Denver region of the state of Colorado. The Census Bureau estimates that the CSA population was 2,998,878 on 2007-07-01, an increase of +14.03% since United States Census 2000. The Denver-Aurora-Boulder CSA is now the 17th most populous metropolitan area and the 14th most populous CSA in the United States. In 2007, 61.7% of Coloradans lived in the Denver-Aurora-Boulder CSA.