I've been going back and forth on this one for a while. Is it worthwhile to split the route into two parts, given that
signage shows it entering Tennessee for a short segment?
KYTC maps show that it follows State Line St, never crossing the line, but one block of State Line St is one-way westbound, meaning that anyone following KY 116 eastbound would need to turn right into Tennessee, and immediately turn left, in order to continue straight. Traffic along the Tennessee diversion is two-way, but westbound travellers could stay on State Line St and never enter Tennessee.
TDOT maps don't acknowledge the route on their side of the state line, unless one considers line thickness important.