From the Disneyland website:
Public Transportation from John Wayne Airport (SNA) to the Disneyland Resort
All ground transportation pick-up locations are situated in the Ground Transportation Center (GTC) within easy walking distance from the baggage claim area. The GTC is located on the Arrival (Lower) Level in the center of the East Parking Structure and can be reached from the Thomas F. Riley Terminal by crossing the airport roadway at the traffic light near the John Wayne Statue.
Disneyland Resort Express
The Disneyland Resort Express provides the most convenient mode of transportation between John Wayne Airport and the Disneyland Resort area, including Disneyland Resort and Anaheim Resort hotels. Upon exiting baggage claim, proceed to the GTC. The Disneyland Resort Express picks up Guests in front of the ticket booth located to the left on a regular basis.
Reservations are not required, but there is a fee to ride.
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