You have to go way back to 1929 to find the first American driver, Charles Moran Jr, to enter the 24 Hours of Le Mans in an American car, a Continental. Five years later, George Stewart was the first American to cross the finish line at the Circuit de la Sarthe, taking 14th place. Italian-born Luigi Chinetti claimed victory in the first post-war 24 Hours in 1949, three years after becoming an American citizen. Finally, in 1958, Phil Hill, became the first driver born in the USA, in Miami, Florida, to climb on to the top step of the Le Mans podium.
Photo (copyright ACO archives): Phil Hill gives Olivier Gendebien a ride on the back of the winning Ferrari 250.