Whether it's flappers and gangsters dancing the Charleston in Prohibition-era speakeasies, or the lavish mansions and automobiles of The Great Gatsby, few eras exert such an outsized influence on the American imagination as the 1920s. To modern eyes the Roaring Twenties seem like an oasis of optimism and prosperity between the catastrophes of the 1910s (the First World War; the Spanish flu pandemic) and the looming dread of the 1930s and the Great Depression. But how roaring were they really?