From Wikipedia:
"The Midwest Old Threshers Reunion was started in 1950 and has taken place every Labor Day weekend since in the small town of Mt. Pleasant, Iowa. Over 100,000 visitors from all over the World flood this tiny town of about 10,000 for a week long celebration which pays tribute to antique agricultural equipment.
Old Threshers Reunion, as an event, attracts visitors from around the world, attracted by both the permanent exhibits on the reunion grounds and by the collections of antique and steam powered equipment brought to the show by other visitors."