It is common to think of the Roaring Twenties as a distinct period in history, bounded on one end by World War I (1914–18) and on the other by the stock market crash and the Great Depression (1929–41), the period of economic downturn and hardship when millions lost their life savings, their jobs, and the sense of security they had once known. The special nature of the 1920s, with its colorful characters, exciting developments and events, and entertaining fads and trends, makes it tempting to frame the decade in that way. It is more accurate, however, to recognize that many of the changes and circumstances of the 1920s were rooted in previous decades. Similarly, the shift to the grim days of the Depression was neither as unexpected, nor as sudden as it may seem. However few people saw the change coming and...