Suffering from the effects of the Great Depression, the Granville Brothers decided in July 1931 to build an aircraft to compete in that fall's Thompson Trophy competition at the National Air Races in Cleveland, Ohio.

[1] Constructed in less than five weeks at a cost of under $5,000 USD, the Gee Bee (for "Granville Brothers") Model Z, named City of Springfield, was a small, tubby airplane.

On September 5, the aircraft's engineer, Bob Hall, flew the Gee Bee Z to victory in the General Tire and Rubber Trophy race, then won again the next day in a free-for-all event.

[4] Shortly after the Thompson Trophy race, the Gee Bee Z was retrofitted with a larger, 750-horsepower (560 kW) Wasp Senior radial engine for an attempt at establishing a world speed record for land planes.

[4] Four days later, on December 5, 1931, a second speed record attempt was made, but the Gee Bee Z's right wing failed catastrophically, causing the air racer to suddenly roll uncontrollably and crash.

[3] Data from [4][7]General characteristics Performance Kermit Weeks, founder of Fantasy of Flight, used a Gee Bee Model Z as his main character "Zee" in a series of children's books set around the interwar period.