How successful was the economic hothouse? a few figures can at least suggest what it did for productivity. During the 1870s American gross national product, measured in 1958 dollars, averaged about $23 billion a year. That figure reached $52.7 billion in 1890, $76.7 billion in 1900, and $125.6 billion in 1914. In per capita terms the amount jumped from $531 in the 1870s to $1,267 in 1914. Between 1839 and 1899 total commodity output rose at a rate of 50 percent every decade. The population also soared but only at about half this rate; as a result, the output per capita in 1899 increased by 250 percent of that of half a century earlier. Nonfarm output per man-hour rose 28 percent during the 1890s despite the depression and jumped another 49 percent by 1919. The number of business concerns went from 427,000 in 1870 to nearly 1.2 million in 1900 and more than 1.8 million in 1920.

Disposable income increased for workers at all levels, driven by earnings that rose while prices fell. Disposable personal income, which averaged $14.1 billion around the turn of the century, reached $33.3 billion by the eve of World War I and soared to $71.5 billion by 1920, thanks in part to wartime inflation.