This is a book about social change in the United States during the twentieth century. It relies on statistical trends to tell that awesome story. The twentieth century was the first century that could be measured in a systematic manner. Those who saw it coming included President James A. Garfield who, while still a congressman in 1869, observed in a speech to the U.S. House of Representatives: The developments of statistics are causing history to be rewritten. Till recently, the historian studied nations in the aggregate, and gave us only the story of princes, dynasties, sieges, and battles…. Now, statistical inquiry leads him into the hovels, homes, workshops, mines, fields, prisons, hospitals, and all other places where human nature displays its weakness and its strength. In these explorations he discovers the seeds of national growth and decay, and thus becomes the prophet of his generation.