1. On December 3, 1804, the Lewis and Clark Expedition entered what is now Montana, marking the first time that non-Indigenous people had ever explored the region. The explorers spent the winter in Montana and encountered many Native American tribes along the way.

2. The town of Butte, Montana was officially incorporated on December 3, 1877. Butte was one of the largest copper mining towns in the world during the late 19th and early 20th centuries, and its legacy can still be seen in the city's architecture, museums, and festivals.

3. December 3, 1910, marked the opening of the Anaconda Road, a highway that linked the towns of Butte, Anaconda, and Deer Lodge. The road was considered a major engineering feat at the time, as it required the construction of a large concrete viaduct over the Clark Fork River.

4. On December 3, 1927, the Towe Ford Museum in Deer Lodge was opened to the public. The museum is dedicated to preserving the history of the Ford Motor Company, and it features a large collection of antique Ford vehicles and memorabilia.

5. December 3, 1972, is a significant date in the history of Montana's state parks system. On this day, the Montana State Parks and Recreation Board was created, setting the stage for the development and management of the state's many parks and recreational areas.