1. In 1804, the Lewis and Clark Expedition entered the present-day state of Wyoming on September 23rd. They traveled near the present-day city of Fort Laramie, where they met with local Native American tribes.

2. On September 23, 1906, the first public library in Cheyenne, Wyoming was dedicated. The library was built with funds donated by Scottish-American philanthropist Andrew Carnegie.

3. The University of Wyoming was founded on September 23, 1886. The first class consisted of only five students, but the university has since grown to become the largest institution of higher education in the state.

4. In 1950, Wyoming became the first state in the United States to allow women to serve on juries. This historic legislation was signed into law on September 23rd.

5. The famous outlaw Butch Cassidy was born as Robert Leroy Parker in Beaver, Utah on September 23, 1866. Cassidy later became known for his bank and train robberies throughout the American West, including several in Wyoming.