1. In 1792, Kentucky became the 15th state to join the United States. After years of being a part of Virginia, the western territories of Kentucky were granted statehood by Congress on May 31.

2. On May 31, 1864, the Battle of Cold Harbor began during the American Civil War. Confederate troops under General Robert E. Lee were able to hold off Union forces under General Ulysses S. Grant in a brutal battle that lasted for weeks.

3. The Kentucky Derby, one of the most famous horse races in the world, often falls on the first Saturday in May. However, in 1941, the race was held on May 31 due to a scheduling conflict with Mother's Day. Whirlaway won the race that year, becoming the fifth horse to win both the Kentucky Derby and the Triple Crown.

4. In 1908, the Lincoln Memorial was dedicated in Washington, D.C. The building was designed by Kentucky-born architect Henry Bacon, who drew inspiration from Greek and Roman architecture. The memorial stands as a tribute to former U.S. President Abraham Lincoln, who played a pivotal role in ending slavery in America.

5. On May 31, 1859, the steamboat United States was engulfed in flames while traveling down the Ohio River. The fire claimed the lives of over 150 people, making it one of the deadliest steamboat accidents in American history. The tragedy highlighted the dangers of steamboat travel and led to increased safety regulations for the industry.