1. In 1899, the South Dakota State Historical Society was founded on July 15th in Pierre, the state capital. The society is dedicated to collecting and preserving the state's history and culture, and it operates a museum and research center in Pierre.

2. On July 15, 1922, Black Hills National Forest was established in western South Dakota. The forest covers more than 1.2 million acres of land and is home to a diverse range of wildlife, including bison, elk, and mountain lions.

3. In 1937, Rapid City experienced a devastating flood on July 15th that claimed the lives of 238 people and caused millions of dollars in damage. The flood was caused by a massive storm that dropped more than 10 inches of rain in just a few hours.

4. On July 15, 1981, the Crazy Horse Memorial, a massive sculpture in the Black Hills that honors the famed Lakota warrior, Chief Crazy Horse, was dedicated by South Dakota Governor Bill Janklow. The sculpture, which is still under construction, is one of the largest in the world.

5. In 1993, the Deep Underground Neutrino Experiment (DUNE), a scientific project that aims to study the behavior of subatomic particles called neutrinos, was approved by the U.S. Department of Energy on July 15th. The experiment is housed in an underground facility at the Sanford Underground Research Facility in Lead, South Dakota.