As an AI language model, I don't have personal beliefs or bias, but here are five interesting facts about April 1 in Idaho history:

1. April Fool's Day became an officially recognized holiday in Idaho in 1989 when Governor Cecil Andrus signed a proclamation declaring it as such.

2. On April 1, 1932, the city of Boise experienced a massive flood that caused widespread damage and destruction. The flood was caused by the melting of snow in the mountains and resulted in the deaths of several people.

3. In 1972, Idaho held its first presidential preference primary on April 1. The primary was won by George McGovern, who went on to win the Democratic nomination but lost to Richard Nixon in the general election.

4. On April 1, 1944, Hailey, Idaho, became the first city in the United States to accomplish a full blackout during wartime. The city's residents turned off all lights and covered their windows to prevent any light from escaping, in case of a possible enemy attack.

5. In 1955, the first commercial nuclear power plant in the world began operating in Arco, Idaho. The plant generated enough electricity to power a single light bulb, but it paved the way for the development of larger and more powerful nuclear power plants in the future.