Leading Causes of Death in 1900 U.S.

Infectious diseases, specifically pneumonia, influenza, and tuberculosis, amounting to a death rate of about 400 per 100,000—with today's population, that would be about 1.3 million deaths a year. (The number might be somewhat lower to the extent some of the pneumonia was noninfectious in origin.) The number of pneumonia and influenza deaths in the U.S. last year was 55,000.