1. On August 21, 1910, the Great Fire of 1910, also known as the Big Blowup, began in northern Idaho. The fire burned over 3 million acres of land in Idaho, Montana, and Washington, killing at least 87 people and destroying many towns.

2. August 21, 1959, marked the beginning of the Idaho National Reactor Testing Station (INL) in eastern Idaho. The INL became a center for nuclear research and development during the Cold War era, and its facilities played a key role in developing the first nuclear submarine and generating the first usable electricity from nuclear power.

3. On August 21, 1972, Richard Nixon visited Boise, Idaho, as part of his re-election campaign. During his visit, Nixon spoke at the state Capitol and visited the Idaho State Fair. This was Nixon's first visit to Idaho as president.

4. August 21, 2006, was the date of the biggest natural gas pipeline disaster in Idaho's history. A rupture occurred in a gas pipeline near the town of Plymouth, causing a massive explosion that killed two people and destroyed several homes.

5. On August 21, 2017, Idaho experienced a partial solar eclipse. The eclipse was visible from almost all parts of the state, with some areas experiencing up to 99% coverage of the sun. Many people in Idaho traveled to locations with the best views of the eclipse, making it a memorable event for the state.