In 1900, what was the leading cause of death in the United States?

• A. Pneumonia
• B. Tuberculosis
• C. Influenza
• D. Measles

Answer: (B)

Tuberculosis was the dominant killer in the United States around 1900 because it spread easily and there was no effective treatment. The disease often progressed slowly, weakening people over time, and crowded urban living conditions helped transmission. The TB bacterium (Mycobacterium tuberculosis) had been identified by 1882, but antibiotics didn’t exist yet, so deaths from TB remained high. Public health efforts like sanatoria and improvements in living conditions reduced spread over the decades, but in 1900 TB still caused more deaths than other infectious diseases. Pneumonia and influenza were significant killers as well, but their mortality impact was not as high as TB at that time, and measles, while deadly for children, did not cause as many deaths overall.