Outhouses can be bought or built; the toilet inside can anything from a one-hole board to a commercial toilet.
Mayor Bill Sanderson says the driver must be on the "throne" inside the outhouse, and must control steering and braking for the gravity-propelled vehicle.
Up to two people can push the vehicles 40 feet, then let them loose to roll downhill.
It's a double elimination race, with two carts per heat.
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