 Even with the Kansas City area's continued growth, 913 is nowhere near exhaustion.NANPA projections of 2017 estimate that the Kansas side of the Kansas City area will not need another area code until 2045.When the 785 split of numbering plan area 913 to removed most of the territory, Wyandotte, Linn, Miami, Johnson, Leavenworth, and Atchison counties kept 913.