Tuesday, July 16 marks the 40th anniversary of the costliest tornado in Wyoming history.

The Cheyenne Office of the National Weather Service posted this overview of the twister which hit Cheyenne on July 16, 1979:

''On July 16, 1979, the most destructive tornado in Wyoming's history occurred at Cheyenne. The main ingredient for the development of the Cheyenne F3 tornado was an outflow boundary from previous thunderstorms moving south across western Nebraska. In addition, abundant mid level moisture spread from the northeast and the presence of low level wind shear enhanced the risk for severe thunderstorms.

The tornado was first reported at 3:10 PM by a weather service employee west of Cheyenne. The tornado began near the intersection of Vandehei Avenue and Valley View Road, and tracked to the east for approximately 9 miles.

The majority of the damage was over residential areas of Buffalo Ridge and a nearby mobile home park. An estimated 200 homes were destroyed with 40 injuries and 1 fatality.

An interactive and zoomable map is available on this 40th Anniversary Dashboard. Use the top half of the page to explore the areas hit by the tornado in 1979 and what infrastructure/roads would be impacted today. The bottom half of the page contains statistics of how many structures, people, and the median house value could be impacted if the tornado occurred today.''