1. In 1863, the Idaho Territory was established by an act of Congress. It initially included all of present-day Idaho, Montana, and Wyoming, as well as parts of present-day Colorado, Nevada, Oregon, Utah, and Washington.

2. In 1883, the first train arrived in Boise, Idaho, marking the completion of the Oregon Short Line Railroad from Huntington, Oregon.

3. In 1925, the Idaho State Capitol building was dedicated in Boise. The building, designed in the neoclassical style, features a central dome and is topped by a bronze eagle.

4. In 1954, the Salmon River Bridge in Riggins, Idaho, was completed. The bridge, which spans the Salmon River canyon, was the highest in the state at the time of its construction.

5. In 1983, the Teton Dam in eastern Idaho failed, resulting in one of the largest and costliest dam failures in U.S. history. The collapse of the dam led to flooding that caused extensive damage to the surrounding farmland and communities.