1. The first known white settler in Idaho, Harry Orchard, was born on May 20, 1866. Orchard later became infamous for assassinating former Governor Frank Steunenberg in 1905.

2. The Idaho State Penitentiary, located in Boise, opened on May 20, 1872. The prison housed some of Idaho's most notorious criminals until it was closed in 1973.

3. On May 20, 1895, the Idaho Legislature approved the creation of the University of Idaho, the state's first public university. Today, the University of Idaho is a leading research institution with campuses in Moscow, Boise, Coeur d'Alene, and Idaho Falls.

4. In 1910, the first airplane flight in Idaho was made on May 20 by aviator Silas Christofferson in Pocatello.

5. On May 20, 2002, the town of Stanley, Idaho was hit by a 6.0 magnitude earthquake, the strongest earthquake to hit the state in over a decade. The quake caused significant damage to homes and buildings, but there were no fatalities.