William Henry Harrison served the shortest presidency in U.S. history, dying only 31 days after taking office.

William Henry Harrison gave his speech on March 4, 1841. The weather was 48 degrees Fahrenheit with cold winds. His speech was 8,445 words long and took nearly two hours to finish. He did not wear a coat, gloves, or a hat during the event.For a long time, people believed the cold weather caused him to get pneumonia. However, modern researchers Jane McHugh and Philip A. Mackowiak studied his symptoms in 2014. They found that the White House water supply was located near a sewage dump. They believe he actually died from enteric fever caused by bacteria in the water.Doctors in 1841 did not know about bacteria. They treated him with painful methods like bloodletting and using heated glass to blister his skin. They also gave him opium and snake weed. These treatments likely made him weaker instead of helping him recover.Harrison died on April 4, 1841. His death caused confusion because the Constitution did not clearly state if the Vice President became the new President. Vice President John Tyler took the oath anyway. This created the rule for how the U.S. handles presidential deaths today.