By the 1920s the automobile was a necesity of American cities. As early as the first decade of the 20th century the practicality and utility of the automobile was evident for many Americans, and whatever limitations existed at the time were viewed as temporary blips that would soon be overcome by the relentless march of progress.
By the mid-twenties, most of these difficulties had been entirely overcome - electric starters, electric headlamps, and reliable, powerful four-and six-cylinder engines were standard on all but the cheapest autos on the market.
Perhaps one of the most important (and overlooked) advances was the development of closed cars - the heavy bodies of sedans required more powerful motors than the anemic engines of early economy cars - in 1919, only one in ten cars purchased was closed-body (most of them in the luxury field), but by 1929 sedans made up 90% of sales.
In terms of statistics, 7.5 million automobiles were registered in the U.S. in 1919; by 1929, that number had grown to 26 million, 23 million of them passenger cars.
This information is based on the source "The Automobile in America" by Stephen W. Sears, and "America Adopts the Automobile 1895-1910" by James Flink
