Small Aircraft
Air Traffic Control Developmental
Situational Awareness; Confusion; Communication Breakdown
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Runway
Air Traffic Control Provided Assistance; Air Traffic Control Issued Advisory / Alert
Procedure; Human Factors; Airport
Aircraft X was cleared to land on Runway 23. Aircraft Y was holding short of Runway 23 at Taxiway E; and Aircraft Z was continuing inbound for Runway 23; having been advised that traffic would be holding in position. Once Aircraft X had passed Taxiway E; Aircraft Y was instructed to line up and wait was as issued traffic for Aircraft Z inbound. Aircraft X was rolling out on Runway 23; and as instructed to turn left onto Taxiway K; Cross Runway 19 on K and contact Ground Control. Aircraft X slowed to taxi speed and was informed no delay off the runway; traffic holding in position; which the pilot acknowledged. Once I visually assured that the tail for the Aircraft X was clear of the runway; I issued a takeoff clearance to Aircraft Y; with a wind check and an instruction to turn left to heading 190. I observed Aircraft Y beginning a departure roll; and then issued a landing clearance to Aircraft Z. The Ground Controller/ICT then informed me that Aircraft X had not completed crossing Runway 19. Aircraft X was informed to continue to pull forward as he was still in the runway environment.  The pilot of Aircraft X then asked if he was cleared to cross Runway 23. Then; I informed the pilot to cross Runway 19 straight ahead and then contact Ground Control. The Ground Controller then taxied the aircraft to parking. [My recommendations are to] improve the airport markings at the Taxiway K; Runway 23 and Runway 19 intersection to make it more clear to pilots which runway they are currently on; or change Taxiway K to parallel Runway 19 south of Runway 23 to join Taxiway F.
CAK Tower Controller reported a runway incursion of a pilot that hadn't fully cleared the runway.