The Automobile Club de l'Ouest (English: Automobile Club of the West), sometimes abbreviated to ACO, is the largest automotive group in France. It was founded in 1906 by car building and racing enthusiasts, and is most famous for being the organising entity behind the annual Le Mans 24 Hours race. The ACO also lobbies on behalf of French drivers on such issues as road building and maintenance, the availability of driving schools and road safety classes, and the incorporation of technical innovations into new vehicles. It also runs a roadside assistance service for its members.
The ACO's history begins with the Automobile Club de la Sarthe, the ancestor of today's ACO, which was founded in the town of Le Mans. In 1906 that group included Amédée Bollée and Paul Jamin, winner of the 1897 Paris-Dieppe race in a Léon Bollée tricar. With the help of the larger Automobile Club de France they organised a race on local public roads, on a 65-mile triangular course connecting Le Mans with Saint-Calais and La Ferté-Bernard. The 12-lap race, titled the Grand Prix de l'ACF, was held over two days and won by Ferenc Szisz driving a Renault, This race, the first Grand Prix, would eventually become the French Grand Prix.
After World War I, the ACO turned its attention to designing a shorter circuit on public roads to the south of the city. The organisation's chief secretary Georges Durand, together with magazine editor Charles Faroux of La Vie Automobile and tyre manufacturer Emile Coquille, came up with the idea for a 24-hour race. The first Le Mans 24 Hours was held on 26 May 1923. The very first entry was lodged with the ACO by John Duff on a Bentley.