As someone who lived in Kansas, just look for the middle of the middle.
The center column of states has 6 states (North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas), and Kansas is in the middle of that vertical line (given that the northern 3 are a bit thinner).
Fun fact, the geographic center of the contiguous states is very near the center of the top edge of Kansas. Including Hawaii and Alaksa, the geopraphic center shifts to the top left corner of South Dakota, just east of where Montana and Wyoming meet.