The boundary between 785 and area code 620, which covers southern Kansas outside of the Wichita metropolitan area, 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. At this point, area code 785 reaches its easternmost boundary with the current boundary for area code 913, although a small portion of the northeast corner of Kansas across the Missouri River from St. Joseph, Missouri is part of 785.
The area code covers the entire counties of Cheyenne, Rawlins, Decatur, Norton, Phillips, Smith, Jewell, Republic, Washington, Nemaha, Marshall, Brown, Sherman, Thomas, Sheridan, Graham, Rooks, Osborne, Mitchell, Lincoln, Cloud, Ottawa, Clay, Riley, Pottawatomie, Jackson, Wallace, Logan, Gove, Trego, Ness, Rush, Ellis, Russell, Ellsworth, Saline, Dickinson, Geary, Wabaunsee, Shawnee, Osage, and Douglas, as well as portions of Atchison, Coffey, Jefferson, Morris and McPherson counties.
The counties of Anderson, Linn, Miami, Johnson, Wyandotte, and Leavenworth remain wholly in area code 913.
One exception to this rule is the city of Elwood in Doniphan County, which retains the 913 area code while the remaining geographical balance of the county is under the 785 area code. This is because Elwood receives its dialtone from St. Joseph, Missouri which is covered by the Kansas City, Missouri LATA, located in area code 816. All bordering 816/913 rate centers have each other's area codes.