The area code 303 is located in Aurora, Colorado.
Area code 303 serves Aurora, Colorado, a fast-growing city just east of Denver in the heart of the Front Range. It anchors the Denver–Aurora–Lakewood metro area and follows Mountain Time (MST/MDT). Introduced as Colorado’s original area code, it remains one of the state’s most recognized phone prefixes. Its location places callers close to major highways, the plains, and quick access to the Rockies.
Area code 303 covers many of the region’s largest communities, including:
Within the 303 footprint, you’ll find top landmarks like the Colorado State Capitol, CU Boulder’s campus, Red Rocks Amphitheatre, the Denver Tech Center, and the CU Anschutz Medical Campus in Aurora. Denver International Airport also serves the metro area covered by 303 and its overlays. These destinations make 303 phone numbers common across business, education, health care, and entertainment in the region.
“303 was one of the original area codes created in 1947 and served all of Colorado until 1988.” — North American Numbering Plan Administrator (NANPA)
Established in 1947, 303 originally covered the entire state before splits created 719 (1988) and 970 (1995). Today, 303 is overlaid by 720 (since 1998) and 983 (added in 2022), so new phone numbers in Aurora and the Denver metro may use any of these codes. Ten-digit dialing is required across the 303/720/983 overlay region. If you see a 303 number, it typically points to the Denver–Boulder–Aurora area within Colorado’s urban core.