1. Idaho Became a State – Perhaps the most significant event that occurred on May 30 in Idaho is the day that it became a state. This happened in the year 1890.

2. Lewis and Clark Expedition Passed Through Idaho – On May 30, 1805, the Lewis and Clark Expedition passed through what is now known as the state of Idaho. The group was traveling from St. Louis to the Pacific Ocean, and their journey took them through what is now Montana, Idaho, and Washington.

3. Union Pacific Railroad Reaches Idaho – In 1883, the Union Pacific Railroad reached Idaho, providing a major boost to the state's economy. The railroad allowed for goods and passengers to travel in and out of the state more quickly and efficiently.

4. The First Passenger Airplane Flight in Boise – On May 30, 1912, the first passenger airplane flight took place in Boise, Idaho. The event featured a Curtiss "Aeroplane" carrying a single passenger around the city.

5. Memorial Day Celebrated – Every year, Memorial Day is celebrated on the last Monday in May. This means that May 30 is sometimes the day on which Idahoans observe this holiday, which honors those who have died serving in the United States Armed Forces.