1. In 1910, the town of Greybull was officially incorporated in Wyoming. Greybull was named after the grey-colored sandstone cliffs that can be found along the Greybull River.

2. The first post office in Rock Springs, Wyoming, was established on June 11, 1881. Rock Springs is known for its history of coal mining and was a popular destination for Chinese immigrants during the late 1800s.

3. On June 11, 1912, Wyoming became the 29th state to ratify the 16th Amendment to the United States Constitution, which authorized the federal government to implement an income tax.

4. The town of Thayne, Wyoming, was named after early pioneer and homesteader, Thayne Kendrick. It was founded on June 11, 1900, and is located in Lincoln County.

5. The famous outlaw Butch Cassidy was born in Beaver, Utah, on April 13, 1866. However, on June 11, 1899, Cassidy and his infamous Wild Bunch gang robbed the Union Pacific Overland Flyer train near Wilcox, Wyoming, successfully making off with over $30,000. The robbery was one of the most daring and successful train robberies in history.