The pilot of the Piper J3C-65 had been practicing banner towing operations, and was landing on runway 9L, a 3,241-foot-long, 100-foot-wide,asphalt runway. After a normal touchdown, the tail-wheel airplane yawed into the wind, and veered off the side of the runway. It then struck a sign and sustained damage to the propeller, landing gear and fuselage. The pilot stated he did not experience any mechanical malfunctions with the airplane. He reported 300 hours of total flight experience, which included 25 hours in the same make and model as the accident airplane. Winds reported at the airport, about 30 minutes prior to the accident, were from 160 degrees at 11 knots, gusting to 17 knots.