How did World War I change Western governments and societies (think politics, economies, and the way people lived)?

World War I required western countries, including the United States, to engage in mass production to make war material. After the war, the western economies, particularly in the U.S., boomed, leading to a great increase in production and consumerism during the 1920s. By the end of the war, the U.S. had emerged as a top world economic power. Politically, after the war, the U.S. entered a period of isolationism and relative conservatism, in part as a reaction against the progressive impulses that had caused the country to get involved in the war. 

Western society also changed during the war. For example, women were employed in large numbers in defense plants in the U.S. and in Great Britain. As a result, after the war, there was increased pressure to give women the right to vote. Women in the United States gained the right to vote in 1920 with the 19th Amendment, and women over 30 in Great Britain gained the right to vote in 1918 (in 1928, women over 21 were given the right to vote in Great Britain). During the 1920s, the "new woman," colloquially called the "flapper," came on the scene in western societies. This type of woman was more liberated and wore less restrictive clothing than women had in previous times. 

In the United States, many African-American people left the south during the start of what was called the Great Migration to work in northern defense plants and other industries. During and after the war, there was a backlash against some of the gains African-Americans had made, leading in part to race riots like the one that occurred in East St. Louis in 1917. Though African-Americans made gains during the war, the 1920s was a time of increased racism in many ways.