1. On August 12, 1937, the Idaho State Penitentiary set a grisly record when six prisoners were executed in one day. This became known as the "Black Thursday Massacre" and is now viewed as a dark chapter in Idaho's history.

2. In 1955, the city of Arco, Idaho became the first city in the world to be powered entirely by nuclear energy. The town had a small experimental reactor that provided electricity for the city's residents.

3. On August 12, 1877, the Nez Perce tribe, led by Chief Joseph, fought a battle against U.S. Army forces in what would become known as the Battle of Big Hole. The Nez Perce were ultimately defeated, and the battle resulted in the deaths of around 90 Nez Perce and 30 U.S. soldiers.

4. August 12, 1915 was the date that the Idaho State Capitol building was dedicated. The building is now a National Historic Landmark and remains the largest and most ornate building in the state.

5. In 1976, the Teton Dam in eastern Idaho collapsed, resulting in one of the worst dam disasters in U.S. history. The collapse caused widespread flooding, resulting in the deaths of 11 people and causing over $1 billion in damage.