1. On March 20, 1883, the Northern Pacific Railroad completed its transcontinental line across Montana. This new transportation route led to increased settlement and economic growth in the state.

2. March 20, 1922, marks the birthdate of Montana native Fred F. Willson, who went on to become a prominent artist and professor at Montana State University. Willson is best known for his Western-themed paintings and sculptures, many of which can be found in public collections throughout the state.

3. March 20, 1950, saw the opening of the Anaconda Smelter, one of the largest copper smelters in the world. The smelter was a major employer for many years in the Anaconda area, but its operations also led to significant environmental damage and pollution.

4. On March 20, 1991, Montana Governor Stan Stephens signed into law a bill that made Montana the first state to allow physician-assisted suicide, under certain conditions. This controversial law was later overturned by the Supreme Court in 2009.

5. Finally, on March 20, 2015, the Montana Historical Society celebrated its 150th anniversary. Founded in 1865, the Historical Society is the oldest cultural institution in Montana, and is dedicated to preserving and sharing the state's heritage and history.