1. Idaho became a state on September 15, 1890. After being a territory for over 26 years, Idaho was officially admitted as the 43rd state in the United States.

2. On September 15, 1902, the Wallace fire occurred. It was one of the most destructive fires in Idaho's history, burning over 13,000 acres and destroying nearly all of the town of Wallace. The fire was caused by sparks from a passing train and was only contained after several days of effort by firefighters.

3. In 1963, Idaho Governor Robert Smylie declared September 15 as Constitution Day in Idaho. This day is now recognized as a time to honor the Constitution and its importance in shaping the United States.

4. On September 15, 1974, the Idaho State Capitol building was added to the National Register of Historic Places. The Capitol building, which was completed in 1912, is one of the most iconic landmarks in Idaho and is still in use today.

5. The first Boise Greenbelt pathway was completed on September 15, 1978. The Greenbelt is a network of pedestrian and bike paths that stretch over 25 miles along the Boise River. It has become a popular recreational spot for locals and visitors alike.