1. On May 9, 1884, the first train arrived in the town of Ketchum, Idaho. The arrival of the railroad spurred growth in the area, leading to an increase in mining and lumber industries.

2. On May 9, 1896, William Borah was elected as a United States Senator from Idaho. Borah served in the Senate for 33 years and was an influential figure in American politics during the early 20th century.

3. On May 9, 1931, the state of Idaho dedicated the Shoshone Falls Dam, which was the highest concrete dam in the world at the time. The dam helped provide irrigation water and hydroelectric power to the surrounding areas.

4. On May 9, 1957, the first Little League season began in Post Falls, Idaho. The league has grown over the years and now includes over 2.4 million players in more than 80 countries worldwide.

5. On May 9, 2013, the Idaho State Capitol Building was reopened to the public after a major renovation project. The building had been closed for over two years while extensive repairs and upgrades were made to the historic structure.