On October 30, 2020, about 1415 central daylight time, a Cessna 140 airplane, N76933, was substantially damaged when it was involved in an accident at South Texas International Airport, Edinburg, Texas. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that during the flight he had performed three uneventful takeoffs and landings in the tailwheel airplane. On the fourth landing, he touched down about 45-50 mph and used a wheel landing technique. The airplane suddenly veered to the right and did not respond to rudder or brake input. The airplane left the paved surface of the runway and traveled into the soft grass covered dirt, at which time the left main landing gear separated from the airplane. The airplane incurred substantial damage to the left wing. The separated landing gear leg was not broken, and the pilot reported that the attachment bolt was not found near the airplane wreckage or on the runway. A mechanic examined the airplane after the accident and found no preimpact mechanical deficiencies but did not elaborate about the retaining bolt. Attempts to contact the mechanic to discuss the retaining bolt were unsuccessful and therefore it could not be evaluated.