The Grand National Roadster Show began in 1950, when Al Slonaker organized a car show in Oakland, California to display 100 hot rods. The first show had 27,000 attendees, and the centerpiece was a 1929 roadster owned by Bill Niekamp that won the coveted America's Most Beautiful Roadster prize.
In the show's first decade, Slonaker expanded it from a pure hot rod exhibition to one that invited many different types of cars and even motorcycles for display. He also instituted a People's Choice award, in order to give the spectators more say in the competition and encourage attendance. The one rule Slonaker established was that any vehicle on display had to be a working one, and at the end of the show, all the cars would fire up their engines and drive in a parade out of the showroom.
Especially in its earliest days, the Grand National Roadster Show was designed to showcase the work of dedicated hobbyists. Many of the cars on display and entered for the AMBR competition were home-built jobs often cobbled together from many different models of car to produce unique vehicles. The first show also featured an exhibit wherein a roadster was built over the course of the show, assembled from parts in only 32 hours. Mechanic Ben Hubbard built the car and successfully fired up the engine on the final night of the show.