1. Montana Statehood Day: August 19 marks the day in 1889 when Montana was officially admitted to the Union as the 41st state. The state has celebrated Montana Statehood Day every year since 1913.

2. The Battle of the Rosebud: On June 17, 1876, a battle was fought between Lakota Sioux and Cheyenne warriors and a U.S. Army column led by General George Crook. The battle took place near the Rosebud Creek in southeastern Montana, and though it ultimately ended in a stalemate, it is considered to be one of the more significant events that led up to the Battle of Little Bighorn.

3. The Lewis and Clark Expedition: On August 19, 1805, the famed Lewis and Clark Expedition passed through what is now Montana on their journey to the Pacific Ocean. The expedition was led by Meriwether Lewis and William Clark, and they were the first known explorers to make their way to the western part of the United States.

4. First Train Through Livingston: On August 19, 1882, the first train arrived in Livingston, Montana. This event marked the completion of the Northern Pacific Railroad's transcontinental line and brought increased commerce and development to the state.

5. Montana's First Newspaper: August 19, 1864, marked the publication of the first newspaper in Montana, called The Montana Post. The paper was printed in Virginia City and was considered an important source of information for miners and settlers in the area. It ultimately ceased publication in 1869 due to financial difficulties.