1. The Lewis and Clark Expedition crossed the Great Falls of the Missouri River on May 5, 1805. The falls were a major obstacle for the explorers, who had to navigate around them with the help of Native American guides.

2. Montana's first territorial governor, Sidney Edgerton, was appointed on May 5, 1863. Edgerton played a key role in establishing Montana's political system and was known for his support of women's suffrage and Native American rights.

3. The state's first oil well was drilled near Billings on May 5, 1915. The well produced a small amount of oil but sparked a major industry in the state.

4. On May 5, 1972, the Montana Constitution was ratified by voters. The new constitution guaranteed a broad range of individual rights and protections, including the right to privacy and a clean environment.

5. Montana's most destructive tornado on record touched down near the town of Colstrip on May 5, 1997. The tornado, which was rated F3 on the Fujita scale, caused significant damage to homes and businesses in the area but no fatalities.