 Under the most recent projections, southern Kansas will not need another area code until the fourth quarter of 2037.The boundary between area codes 620 and 785 runs from west to east roughly following a path along K-4 and K-96.The code boundary dips along I-135 in McPherson County and continues east to just north of Emporia in Lyon County along the Kansas Turnpike, where the boundaries of area codes 620, 785 and 913 meet.