1. The Lewis and Clark Expedition crossed the Continental Divide on March 25, 1806. The team, led by Meriwether Lewis and William Clark, was exploring the Louisiana Territory and ventured over the Rocky Mountains. This date marked a significant moment in their journey.

2. The city of Helena, Montana was founded on March 25, 1864. It was named after the capital of the state of Minnesota, and quickly grew as a center for mining and commerce in the area.

3. Montana became a state on November 8, 1889, but on March 25, 1971, it adopted a new state constitution. This constitution established new protections for civil rights, education, and the environment.

4. On March 25, 1931, the U.S. Congress appropriated funds to build the Fort Peck Dam on the Missouri River in Montana. The dam would become a major source of hydroelectric power for the state, supplying energy to areas as far away as Seattle.

5. The Great Falls International Airport opened on March 25, 1940. The airport serves as a major transportation hub for the state, connecting Montana to the rest of the country and the world. It has also played an important role in military aviation, serving as a training ground for bomber pilots during World War II.