1. In 1977, the deadliest tornado in South Dakota history struck the town of Wessington Springs on June 26th. This F4 tornado destroyed buildings, downed power lines, and caused extensive damage throughout the town.

2. On June 26, 1884, the Black Hills Gold Rush officially began with the arrival of the first white prospectors in the region. This event led to a significant influx of settlers and the establishment of several towns in the area.

3. In 1974, former South Dakota Governor Ralph Herseth passed away on June 26th. Herseth was instrumental in the passage of several significant pieces of legislation, including the creation of the South Dakota Housing Development Authority and the establishment of the state's public broadcasting network.

4. On June 26, 2013, the U.S. Supreme Court issued a landmark ruling in the case of United States v. Windsor, striking down part of the Defense of Marriage Act. This decision paved the way for the legalization of same-sex marriage in South Dakota in 2015.

5. South Dakota's first female governor, Nellie Tayloe Ross, was born on June 26, 1876. Ross served as governor of Wyoming from 1925 to 1927 and later became the first woman to serve as director of the U.S. Mint.