1. On September 17, 1863, Union and Confederate forces clashed near Mullan, Idaho, in what became known as the Skirmish on the Coeur d'Alene River. Union soldiers ambushed a Confederate wagon train and captured 30 prisoners and a substantial amount of supplies.

2. In 1904, the Idaho State Fair opened in Boise on September 17. It is one of the oldest and largest state fairs in the United States, drawing over 250,000 visitors annually for a 10-day event showcasing the state's agriculture, industry, and culture.

3. On September 17, 1934, the Sawtooth National Recreation Area was established in central Idaho. It encompasses over 750,000 acres of stunning mountain landscapes, including the Sawtooth Mountains and several lakes and rivers. It is a popular destination for hiking, camping, fishing, and other outdoor activities.

4. In 1978, Idaho became the first state to eliminate the death penalty since its reinstatement by the U.S. Supreme Court in 1976. On September 17 of that year, Governor John Evans signed a bill replacing capital punishment with life imprisonment without the possibility of parole.

5. On September 17, 2011, the Occupy Boise movement held its first protest at the statehouse in Boise. Inspired by the larger Occupy Wall Street movement, protesters camped out on the grounds for several months, calling for economic and political reforms. The movement drew national attention and sparked a conversation about income inequality and corporate influence on government.