Incumbent President James K. Polk had not intended to run for reelection in the 1848 election, and had accomplished everything he had set out to accomplish during his term. He developed health issues, and died a few months after the end of his term. The Democratic Party instead selected Lewis Cass as their presidential candidate. Cass, like election frontrunner Zachary Taylor, had a military background. William Orlando Butler, who served with Taylor in the Mexican-American War, to be his running mate.
The Free Soil Party formed as a single-issue third party in 1848 for the abolition of slavery. The Free Soil Party chose Martin Van Buren as their presidential nominee, with Charles Francis Adams (the son of John Quincy Adams) as his running mate.
The 1848 election was the first presidential election in the United States to hold Election Day on the same day in every state across the country. The Tuesday after the first Monday in November was designated as the official Election Day for the country, a custom which is still used today. The election of 1848 was held on November 7.
Zachary Taylor defeated Lewis Cass with 163 of the 290 total electoral votes, though the margin of victory was much slimmer in the popular vote count. The Free Soil Party, while they did not receive any electoral votes, did receive a substantial percentage of popular votes, which would probably have gone to the Democratic Party.
Taylor died about sixteen months into his term, on July 9, 1850. He was succeeded by his vice president, Millard Fillmore