1. In 1873, the Battle of Lost Canyon occurred in southwestern Minnesota between Dakota Indians and U.S. Army troops. This was one of many conflicts in the Dakota War of 1862.

2. The Minneapolis Aquatennial, a summertime festival featuring water-related events and parades, was first held on May 27, 1940. It continues to be a popular annual event in downtown Minneapolis.

3. On May 27, 1964, the Mauna Loa Observatory in Hawaii recorded the first ever carbon dioxide reading above 320 parts per million (ppm). This milestone marked a significant increase in the presence of greenhouse gases in the Earth's atmosphere.

4. The wreck of the Edmund Fitzgerald, a giant ore carrier that sank in Lake Superior during a storm in 1975, inspired the popular Gordon Lightfoot song "The Wreck of the Edmund Fitzgerald." The ship was partly loaded with taconite pellets from the Iron Range in Minnesota.

5. In 2004, Minnesota became the first state to ban the use of mercury-containing light switches, thermostats, and other devices that can release the toxic metal into the environment. This law, which took effect on May 27 of that year, helped reduce mercury pollution in the state.