John Tyler was significant for being the first vice president to become president because of the death of his predecessor. The predecessor is pretty much the President, that being President William Henry Harrison, the 9th President of the United States. Because President Harrison died from a fever in 1841, John Tyler automatically became the 10th President of the United States. That's how the U.S presidential line of succession works, if the President dies, the Vice President automatically becomes to President of the United States. John Tyler served as the U.S President for 1 term (4 years). Then he passed away on January 18, 1862.