1. Idaho officially became a state on October 31, 1890, making it the 43rd state in the United States. The state had previously been a territory since 1863.

2. The highest temperature ever recorded in Idaho occurred on October 31, 1943, in Orofino, Idaho. The temperature topped out at a scorching 113 degrees Fahrenheit.

3. October 31, 1914, saw the completion of the Arrowrock Dam on the Boise River, which helped to provide water for irrigation and power generation in the region.

4. In 1938, on October 31, the first commercial airline service landed in Idaho. Northwest Airways began flying to Boise from Seattle and Minneapolis.

5. On October 31, 2005, a record-breaking snowstorm hit Idaho, causing power outages, school closures, and severe travel disruptions. Some areas received over three feet of snow in just two days.