The inauguration of William Henry Harrison as the ninth President of the United States took place on March 4, 1841. Tyler was inaugurated as Vice President on the same day. Harrison's inauguration was marked by several firsts: he was the first president-elect to arrive in Washington, D.C. by train, and for the first time an official inaugural committee of citizens had formed to plan the day's parade and Inaugural ball.

The day of Harrison's inauguration was overcast with a cold wind and a noon temperature estimated to be 48 degrees Fahrenheit. Harrison chose to not wear an overcoat, hat, or gloves for the ceremony. He wanted to present a robust image to counter public concerns that at age 68 (the oldest president to be inaugurated at the that point in time) he was too old for the job. He was sworn in by Supreme Court Chief Justice Roger B. Taney on the East Portico of the United States Capitol. According to the Library of Congress, it is unknown what bible he used, but he did follow precedent by swearing the oath of office on the bible.
Harrison proceeded to deliver the longest inaugural address in American history, running 8,445 words. Harrison wrote the entire speech himself, though it was edited by soon-to-be Secretary of State, Daniel Webster. Webster said afterwards that in the process of reducing the text, he had "killed seventeen Roman proconsuls."
That evening Harrison attended three inaugural balls, including one at Carusi's Saloon entitled the "Tippecanoe" ball, which at a price of US$10 per person attracted 1000 guests.

There is disagreement as to whether or not Harrison picked up a cold that day which led to his death a month later on April 4, 1841. This theory is disputed by Harrison's biographer Freeman Cleaves in his 1939 bio Old Tippecanoe: William Henry Harrison and His Time. According to Cleaves, Harrison didn't pick up his cold until March 26, over three weeks after the Inauguration. The cold worsened, rapidly turning to pneumonia and pleurisy. Harrison sought to rest in the White House, but could not find a quiet room because of the steady crowd of office seekers. His extremely busy social schedule made any rest time scarce. Harrison's doctors tried cures, applying opium, castor oil, leeches, and Virginia snakeweed. But the treatments only made Harrison worse, and he became delirious. He died at 12:30 am on April 4, 1841, of right lower lobe pneumonia, jaundice, and overwhelming septicemia. He was the first United States president to die in office. His last words were to his doctor, but assumed to be directed at John Tyler, "Sir, I wish you to understand the true principles of the government. I wish them carried out. I ask nothing more."