1. Oklahoma became the 46th state in the United States on May 20, 1907. The area was previously known as Indian Territory and was settled by numerous Native American tribes, including the Cherokee, Chickasaw, Choctaw, Creek, and Seminole.

2. On May 20, 2013, a devastating tornado struck the city of Moore, Oklahoma, causing widespread destruction and numerous fatalities. The tornado was rated an EF5, the highest level on the Enhanced Fujita scale, with winds exceeding 200 miles per hour.

3. May 20 is also the birthday of Oklahoma native and country music legend, Bob Wills. Wills was born in 1905 in the town of Kosse and went on to become one of the most influential musicians in the genre of Western swing.

4. In 1932, aviator Wiley Post became the first person to fly solo around the world, completing the feat on May 20 of that year. Post was born in the town of Grand Saline, Texas, but spent most of his adult life in Oklahoma and is buried in the state.

5. On May 20, 1875, the state's first post office was established in the town of Norman, Oklahoma. The postmaster was J.R. Leeper, and the town had a population of less than 500 people at the time. Today, Norman is home to the University of Oklahoma, one of the state's largest and most prestigious institutions of higher learning.