1. The first Oklahoman to win a Pulitzer Prize was born on April 15, 1944. Michael Bliss, a historian and professor, won the Pulitzer Prize for his book "Plague: A Story of Smallpox in Montreal."

2. On April 15, 1935, Oklahoma experienced the worst dust storm in history, known as Black Sunday. The storm caused widespread damage and led to many deaths and respiratory illnesses.

3. The Oklahoma City bombing occurred on April 15, 1995, when a truck bomb exploded outside the Alfred P. Murrah Federal Building, killing 168 people and injuring hundreds more.

4. On April 15, 1898, the Spanish-American War began, and Oklahoma Territory sent the first two troops of cavalry to fight in the war. The soldiers were part of the First Territorial Cavalry, consisting of 120 men.

5. April 15, 1907, marks the day when Oklahoma became the 46th state in the United States. It was the result of the Oklahoma Enabling Act, which allowed the territories of Oklahoma and Indian Territory to form a single state.