Date: 201908
Local time of day: 1801-2400
Location: MDW.Airport, IL
Flight conditions: VMC
Light: Night
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground MDW
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion
Second reporter function: Pilot Flying; Captain
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Became Reoriented
Contributing factors: Airport; Human Factors
Primary problem: Human Factors

Narrative: RNAV Y to 22L in VMC conditions at ZZZ. Night landing configured flaps 30 max braking. Busy night with traffic volume. Uneventful landing but due to max brakes; we slowed well prior to Taxiway Kilo. As a result; due to traffic close behind us; Tower asked if we could exit at Runway 31L. We responded we could do that; and the PF began turning the aircraft to exit at 31L; we thought. As the aircraft turned off the runway and after our nose was committed to the exit point; I mentioned it looked very narrow and is this actually Foxtrot and we noticed it didn't appear to be Runway 31L.The PF (Pilot Flying) stopped the aircraft with the nose in what turned out to be Taxiway Foxtrot and the rear of the aircraft still on the runway. I; PM (Pilot Monitoring); tried multiple times to contact Tower; but there was too much traffic and I was not successful. Simultaneously; the PF assessed the options he had of either trying a hard right turn back on to the runway to continue down toward Kilo or to continue the short distance on Foxtrot then make a left turn to join Yankee. Due to concern about making the right turn and the left main possibly leaving the pavement; the PF made the decision to continue on Foxtrot while carefully staying on center line. The rest of the taxi in was uneventful.1) Taxiway F not emphasized in the approach brief. 2) Night operations; coupled with the very close proximity of 31L and F renders the visual cue of 31L; a very narrow runway; and Taxiway F very similar looking upon initiating turnoff. 3) Max brakes brought the aircraft to a stop much earlier than the normal turnoff of Taxiway Kilo; resulting in an unfamiliar turnoff scenario. 4) Heavy landing traffic and consequential radio chatter. Several things could have helped to prevent this situation: 1) If the box on the airport plan Jepps Chart referencing Taxiways A and F were highlighted in red; it would bring more attention to it during the approach brief; putting the fact that Taxiway F IMMEDIATELY follows Runway 31L when landing 22L; both looking very similar in terms of width; in the forefront of both pilots' minds. Maybe add to that any red box items on Jepps charts are required in the appropriate briefs; takeoff/departure or arrival/approach/landing. 2) It would be helpful for MDW to paint turnoff lines both at 31L and at Taxiway Kilo; again adding to visual reference leading to instinctive turnoffs at either of those points; avoiding mistaking turning at Taxiway F as a viable option. 3) Finally; if Tower requests an exit at Runway 31L; they should in the same sentence; state that 'if unable 31L; exit at Kilo.' Again; this would raise/reinforce a red flag that there is a potential exit following 31L that should not be used.


Second narrative: [Report narrative contained no additional information.]


Synopsis: B737 flight crew reported turning early onto taxiway instead of continuing to correct exit from runway.