1. Idaho became a state
On August 20, 1890, Idaho was admitted as the 43rd state of the United States. This event marked the end of a long struggle that began when settlers first started arriving in the area back in the 1860s.

2. The Battle of Bear Valley
The Battle of Bear Valley was a skirmish that took place on August 20, 1864, during the Snake War. The battle saw a small group of US Army soldiers confront a much larger force of Shoshone warriors, resulting in a victory for the army.

3. The establishment of Idaho's first capital
On August 20, 1864, the newly formed Idaho Territory established its first capital in Lewiston. Previously, the territory had been administered by the Washington Territory, but as the number of settlers increased, it became clear that Idaho needed its own government.

4. The opening of the Payette National Forest
August 20, 1906, saw the creation of the Payette National Forest, a large area of preserved wilderness located in central Idaho. The forest is home to a diverse range of plants and animals, including elk, mule deer, and grizzly bears.

5. The Boise River flood of 1952
On August 20, 1952, the Boise River experienced a catastrophic flood that caused significant damage to the city of Boise and the surrounding area. The flood was caused by heavy rainfall combined with melting snowpack, and it resulted in the deaths of 25 people and caused over $100 million in damages.