1. On October 16, 1940, the U.S. government began construction on the Fort Peck Dam, the largest hydraulics project in the world at the time, in northeastern Montana. The dam was completed in 1943 and created Fort Peck Lake, which covers over 240,000 acres.

2. In 1805, the Lewis and Clark expedition camped near modern-day Livingston on October 16. This marked their first encounter with grizzly bears, as several of the animals raided their camp during the night.

3. On October 16, 1877, Nez Perce leader Chief Joseph led his band of around 800 people through the Big Hole Valley in western Montana. The Nez Perce were fleeing the U.S. Army after resisting forced removal from their ancestral lands in what is now Idaho.

4. Montana became a state on November 8, 1889, but on October 16 of that year, the Montana Constitutional Convention convened in Helena to draft the state's constitution. The document was completed in just 40 days and served as Montana's governing document until a new constitution was adopted in 1972.

5. In 1906, the historic Northern Pacific Railway Depot opened in Helena on October 16. The depot served as a hub for passenger and freight transportation in and out of the capital city until it was decommissioned in 1971. Today, the depot houses offices for state agencies and is listed on the National Register of Historic Places.