303 Area Code: Denver, Colorado

Denver is the primary city of the 303 area code, the original code for the broader Denver metropolitan region. Denver sits on the high plains immediately east of the Front Range of the Rocky Mountains, at an elevation of roughly a mile above sea level — the famous mile-high benchmark sits on the Colorado State Capitol's west steps. The city's working economy combines federal employment, a substantial energy and mining services sector, and a fast-growing technology corridor, all set against a metropolitan footprint that has expanded dramatically through recent decades.

Other Colorado cities — Colorado Springs and Fort Collins among them — appear in the directory's records tied to 303 numbers. Neither is inside the 303 footprint; their recurrence reflects how Front Range numbers and addresses link across the region through porting, prior registration, and routine cross-referencing in public records. We currently document 680 distinct prefixes within 303 in detail, a working subset of the prefixes actually carried by the code.

Denver's home values run substantially above the US median, in line with the broader Front Range pricing pattern that has reshaped housing costs across Colorado over the past decade. Median household income sits well above the national reading, the city's median age lands a few years under the US figure, and the population places Denver among the larger Mountain West metros — sizable enough to anchor a regional economy that pulls steadily on populations across Colorado, Wyoming, and the surrounding states.