1. In 1870, the first railroad in Montana was completed on October 12th. The Northern Pacific Railroad connected Lake Superior to Puget Sound and passed through Montana, bringing new opportunities for transportation and commerce to the state.

2. On October 12, 1915, the University of Montana's iconic Main Hall building opened to students. The building, designed in the Renaissance Revival style, remains a prominent landmark on campus.

3. The Montana State Flag was adopted on October 12, 1905, featuring the Montana State seal on a blue field with the words "Montana" and "Oro y Plata" (Spanish for "Gold and Silver") beneath it.

4. In 1933, on October 12th, Montana's largest earthquake in recorded history occurred near Helena with a magnitude of 6.2 on the Richter scale. The quake caused severe damage to buildings and infrastructure in the area, but no fatalities were reported.

5. On October 12th, 1974, Native American activist Leonard Peltier was apprehended by Canadian authorities at the Alberta border. Peltier was later convicted of the murders of two FBI agents on the Pine Ridge Indian Reservation in South Dakota and remains a controversial figure in Native American civil rights history.