How U.S. ‘mass motorization’ happened

From the Atlantic Cities: "Mass motorization occurred earlier in the United States than in Europe, mainly facilitated by assembly line production that brought down cost. By the mid-1930s there was already one registered automobile for every two U.S. households, while car ownership in Europe was mostly limited to wealthy elites. Moreover, greater personal wealth in the U.S. allowed households to more readily afford cars than comparatively poorer European households, particularly in the years immediately after World War II."