RETURN World War I 

As Europe was plunged into war in 1914 the US initially remained preoccupied with events closer to home. The economic dimension of American imperialism in the Caribbean and central America became increasingly evident. Under President Wilson in 1915 American troops were stationed in Haiti to protect American business interests there and the following year he did the same in the Dominican Republic. Nicaragua was also brought under American control. The Mexican port of Veracruz was occupied by US troops in 1914 as part of a campaign to unseat the dictator Victoriano Huerta, contributing to the chaos into which Mexico was descending. 

America’s role in the European conflict was initially that of a mediator, but German submarine attacks on supposedly neutral shipping led to growing public acceptance of a more aggressive role for the US. In April 1917 the US entered the war on the Allied side. More than a million troops were dispatched and by November 11 the Germans capitulated. Wilson tried to engineer a peace based on a set of principles contained in his "Fourteen Points" declaration which included free international trade, world disarmament, and creation of a "League of Nations" organization which would see to it that international conflicts would be resolved without war. Little of this was of interest to the other Allies. Wilson’s League of Nations did come into being, but few were optimistic about its likely effectiveness, especially when the US Congress failed to support Wilson’s program, including US membership in the League of Nations itself. 

The 1920s and 1930s saw the US return to its more traditional preoccupation with its own internal affairs, in the 1920s dominated by growth and prosperity and the 1930s by depression and uncertainty. 

The US census of 1920 showed that for the first time more Americans lived in cities with populations greater than 2500 than elsewhere. The decade was marked by technological and other changes that were also serving to transform the nature of daily life for most Americans. The automobile culture initiated by Henry Ford took hold, while new forms of communication, moving pictures, the telephone and the radio became familiar to the great bulk of the population. Extension of the franchise to women through the 19th Amendment in 1920 enabled women to vote in national elections and the long struggle of feminists to break down barriers to the participation of women in business, the professions, and other aspects of social life long reserved for males began to yield results. Capitalism in America appeared to be living up to the promises of its supporters. Through the entire decade Republicans dominated federal politics, electing three successive presidential candidates, all of whom stood for traditional Republican values, government support of business and what were coming to be seen as a distinctive American way of life. 

This American way of life did not, however, extend to all who lived there. The large influx of immigrants from central Europe, which had begun in the 1890s and which resumed after World War I, included substantial numbers of Jews, Roman Catholics and other non—Protestant, non-white, or non English-speaking people. This raised fears of the country being overrun by "un-American" influences, fears which were aggravated by developments in Russia where the Revolution had apparently demonstrated the possibility of a radical restructuring of economic life along non-capitalist lines. American immigration law was altered in 1924 to implement a quota system to restrict immigration from countries other than northern and western Europe. Another defensive social measure, the 18th Amendment was ratified in 1919, prohibiting the sale and consumption of alcohol in the US, a drastic move supported not only by the temperance organizations, but also by others who saw it as an assertion of conservative, mainstream American values over those of new-comers whose life-styles were "different". Conservatives also feared the changes which were taking place with respect to American "Negroes", large numbers of whom were leaving the south to seek a better life in the booming cities of the north. The racist supporters of the Ku Klux Klan were if anything more numerous and more violent in these northern cities than in the south and their opposition to Jews and Catholics broadened the appeal of the movement to the extent that it even gained a foothold as far north as Canada with its minute black minority.