1. On August 21, 1955, the Louisville and Nashville Railroad's passenger train, the Humming Bird, was involved in a head-on collision with a freight train near Shepherdsville, Kentucky. The accident resulted in the deaths of 34 passengers and crew members and injured 200 others, making it one of the deadliest train accidents in Kentucky history.

2. August 21, 1862, was the date of the Battle of Richmond, a Civil War battle that took place in Madison County, Kentucky. Confederate forces, commanded by General Edmund Kirby Smith, defeated Union forces led by General William "Bull" Nelson, resulting in approximately 5,300 total casualties.

3. The total solar eclipse that occurred on August 21, 2017, was visible in Kentucky and was a major event for astronomers and eclipse-chasers. Parts of Western Kentucky were in the path of totality, including Hopkinsville, which had the longest duration of totality in the United States.

4. August 21, 1856, marked the opening of the Southern Exposition, a world's fair-style event that took place in Louisville, Kentucky over the course of several years. The exposition showcased agricultural and industrial products from around the region and attracted millions of visitors.

5. On August 21, 1780, during the Revolutionary War, the Battle of Hanging Rock took place in present-day South Carolina, but Kentucky troops played a significant role in the battle. Around 400 Kentucky militiamen, led by Colonel Thomas Sumter, fought alongside Patriot forces and helped secure a key victory over British and Loyalist troops.