1. In 1792, Kentucky became the 15th state to join the Union. The state was originally part of Virginia until it split off to become its own entity.

2. On June 15, 1864, the Battle of Petersburg began during the American Civil War. Union forces under General Ulysses S. Grant attacked Confederate-held Petersburg, Virginia in an effort to break through the defenses and capture the city.

3. Famous boxer Muhammad Ali was born in Louisville, Kentucky on June 15, 1942. Ali is considered one of the greatest athletes of all time and was known for his bold personality both in and out of the ring.

4. The Kentucky Derby, one of the most famous horse races in the world, is traditionally held on the first Saturday in May. However, in 2013, the race was postponed to June 15 due to heavy rain.

5. In 2015, the Supreme Court of the United States ruled in favor of same-sex marriage in the landmark case of Obergefell v. Hodges. One of the plaintiffs in the case, Jim Obergefell, was originally from Cincinnati, Ohio but moved to Kentucky where he met and fell in love with his now-husband John Arthur.