1. On May 13, 1864, the legislature of the Montana Territory passed a law that established a board of commissioners to oversee the laying out of towns and cities within the territory. This helped to establish many of the towns and cities that still exist in Montana today.

2. May 13, 1943 marks the day when Montana native and World War II hero PFC Leo J. K. Chaussee was killed in action during a battle in North Africa. Chaussee was posthumously awarded the Silver Star for his bravery in combat.

3. On May 13, 1958, the Montana Supreme Court ruled in the case of State v. Thompson, which established that the state had the authority to regulate hunting and fishing on Indian reservations within its borders. The decision had significant implications for the relationship between the state and tribal governments in Montana.

4. In 1972, May 13 was the date of the dedication ceremony for Montana State University Billings' new science building. The state-of-the-art facility was named after Dr. William A. McMullen, a longtime MSU professor and administrator who was instrumental in the growth of the university.

5. May 13, 2015 was a notable day for Montana politics: it was the day that Governor Steve Bullock signed the state's Medicaid expansion bill into law. The expansion provided health care coverage for tens of thousands of low-income Montanans who previously lacked access to affordable health care.