1. On July 13, 1787, the Northwest Ordinance was passed, which established the territory that included what is now South Dakota. The ordinance also set forth rules for admitting new states to the Union, including a requirement for freedom of religion, trial by jury, and public education.

2. In 1868, the Fort Laramie Treaty was signed on July 13, which established the Great Sioux Reservation in South Dakota. The treaty was meant to provide land for the Sioux people to live on and protect them from white settlers, but was ultimately broken by the United States government.

3. On July 13, 1905, the famous pioneer and author Laura Ingalls Wilder married Almanzo Wilder in De Smet, South Dakota. The couple had a daughter named Rose, who later helped Laura edit and publish her popular Little House books.

4. The Sturgis Motorcycle Rally, which is now one of the largest motorcycle events in the world, began on July 13, 1938, when a group of riders gathered for a race in Sturgis, South Dakota. The rally now attracts hundreds of thousands of visitors each year and generates millions of dollars for the state's economy.

5. On July 13, 1972, the Black Hills Flood occurred in Rapid City, South Dakota, which killed 238 people and caused millions of dollars in damage. The flood was caused by heavy rainfall and inadequate flood control measures in the city.