1. On March 21, 1959, the Wyoming House of Representatives approved a proposal to create a state flag. The design that was eventually chosen features a blue field with a white bison in the center and two crossed blue columns.

2. Wyoming's first female governor, Nellie Tayloe Ross, took office on March 21, 1925. She had previously served as the first female director of the United States Mint.

3. The famous Outlaw Trail that ran through Wyoming was a popular route for a number of notorious outlaws, including Butch Cassidy and his gang. On March 21, 1896, Cassidy and several other gang members were indicted for robbing the Pleasant Valley Coal Company in Rock Springs.

4. On March 21, 1872, President Ulysses S. Grant signed a bill that established Yellowstone National Park. The park spans over 2.2 million acres across Wyoming, Montana, and Idaho.

5. In the early 1900s, Wyoming was a hotspot for sheep ranching. On March 21, 1918, the Wyoming Wool Growers Association was founded. The organization is still active today and works to promote the interests of sheep ranchers in the state.