1. San Jacinto Day: April 23 marks the anniversary of the Battle of San Jacinto, which took place in 1836 and resulted in the Texan army's victory over Mexican forces. This victory secured Texas' independence from Mexico, making it an important day in Texas history.

2. Texas Flag Day: On April 23, 1933, the Texas legislature officially adopted the Lone Star Flag as the state's official flag. Today, April 23 is commemorated as Texas Flag Day.

3. Rice University Founding: On April 23, 1912, the William Marsh Rice Institute for the Advancement of Literature, Science, and Art was established in Houston, Texas. The name was later changed to Rice University, and it has become one of the most prestigious institutions of higher learning in the United States.

4. Willie Nelson's Birthday: April 23 is the birthday of legendary country music singer and songwriter Willie Nelson. Born in Abbott, Texas in 1933, Nelson is known for his hits such as "Crazy," "On the Road Again," and "Always on My Mind."

5. NASA's First Manned Spaceflight: On April 23, 1962, astronaut Walter "Wally" Schirra piloted the Mercury-Atlas 8 spacecraft on a six-orbit flight around the Earth. This was the fifth manned spaceflight of the NASA Mercury program and the first to carry a camera. Schirra later became one of the original seven Mercury astronauts.