Area codes 303, 720, and 983

Area codes 303, 720, and 983 are area codes that are part of Colorado. 303 was one of the earliest area codes ever made in 1947. It used to cover the entire state of Colorado, but after it was split by 719 in 1988^[1] and 970 in 1995,^[2] it now covers the middle area of the state, specifically in the Denver and Boulder area. It was overlaid by 720 in 1998.^[3] That area was also overlaid by 983 on June 17, 2022.^[4]