The still powerful influence of tradional Protestantism was evident in enforcement of prohibition, made possible by the 18th Amendment (1919; repealed by the 21st Amendment, 1933) and in legislation enacted (1924) to limit immigration from eastern and central Europe. It could also be seen in the 1925 Scopes Trial, which tested (and approved) a Tennessee law against the teaching of evolution in schools; opposition to the 1928 presidential candidacy of New York governor Alfred E. Smith, a Roman Catholic; and the activities of the Ku Klux Klan aimed at Catholics, Jews, and blacks. By the 1920s, industry had completed its takeover of the economy, and the myth of America as a prosperous agrarian society was now more mythical than ever; farmers struggled throughout the decade. Labor unions, already weak, lost ground. Membership declined from 5.1 million in 1920 to 4.3 million in 1929.
Automobiles reveal the impact of technology: by 1929 there were 27 million passenger cars on American streets and roads-triple the number of a decade earlier. The love affair with the automobile stimulated buying on the installment plan, trade-ins, planned obsolescence, and highway-construction programs, and it moved courtship from front porches to the back seats of cars. Along with automobiles, movies with sound, radios, vacuum cleaners, washing machines, and other conveniences became signs of the times.