1. On June 27, 1877, the Battle of the Little Bighorn, also known as Custer's Last Stand, took place in southeastern Montana. Lieutenant Colonel George Armstrong Custer and his troops were defeated by a coalition of Native American tribes led by Sitting Bull and Crazy Horse.

2. June 27, 1914, marked the opening day of the first annual Montana Chautauqua, a traveling educational and cultural event that toured the state for several years. It featured lectures, music, theater, and other entertainment.

3. In 1944, on June 27, the Great Northern Railway's Empire Builder passenger train derailed near Bainville, Montana. The accident resulted in 47 deaths and 75 injuries, making it one of the deadliest train wrecks in Montana history.

4. On June 27, 1977, the first Crow Fair was held on the Crow Indian Reservation in southeastern Montana. The annual event celebrates Crow culture and traditions and attracts visitors from across the country.

5. June 27, 1993, saw the official opening of the Museum of the Rockies in Bozeman, Montana. The museum features exhibits on Montana's natural and cultural history, including dinosaur fossils, Native American artifacts, and pioneer history. It is affiliated with Montana State University.