1. On April 15, 1872, Yellowstone National Park was established by an Act of Congress, making it the first national park in the world. The park spans northwestern Wyoming and parts of Montana and Idaho, and is known for its geysers, hot springs, and wildlife.

2. Wyoming was admitted as the 44th state on July 10, 1890, but on April 15 of the same year, the Wyoming Constitutional Convention began in Cheyenne. The convention ultimately produced the state's first constitution, which was ratified by the residents of Wyoming later that year.

3. The infamous "Johnson County War" began on April 15, 1892, when a posse of armed cattle ranchers and hired guns attempted to capture a group of alleged cattle rustlers in Johnson County, Wyoming. The events that followed included a siege, a trial, and eventually a shootout that left several people dead.

4. On April 15, 1947, a massive blizzard known as the "Holy Week Storm" struck Wyoming and other parts of the central United States. The blizzard raged for several days, dumping more than two feet of snow in some areas and causing widespread power outages and transportation disruptions.

5. On April 15, 1996, a group of extremists calling themselves the "Freemen" were arrested in Jordan, Montana, after an 81-day standoff with law enforcement. The group, which had ties to antigovernment and white supremacist movements, had fled to a ranch in Montana after being indicted on a variety of charges, including bank fraud and weapons violations.