KY actually has a functioning and very aggressive state D party & has been D-controlled at the state, legislative, and court level for much longer than the R-dominated TN, even as TN usually votes slightly to the left of KY in presidential races. As similar as they may be otherwise, the two states couldn’t be any more different when it comes to this (and I don’t think there is another pair of bordering states where the contrast is this noticeable).
Are you sure? R took over KT senate a few years earlier than TN senate.