1. On May 21, 1836, the Battle of San Jacinto occurred in present-day Harris County, Texas. This battle was a pivotal moment in the Texas Revolution, as Texan forces under General Sam Houston defeated the Mexican army under General Antonio López de Santa Anna, effectively securing Texas' independence from Mexico.

2. On May 21, 1881, the infamous shootout between lawman Pat Garrett and outlaw Billy the Kid occurred in Fort Sumner, New Mexico. While this event did not take place in Texas, Billy the Kid was a notorious figure in the state's history, having spent time in various Texas towns and being widely associated with the Wild West era.

3. May 21, 1943 marked the opening of the Big Bend National Park in southwestern Texas. This national park encompasses over 800,000 acres of rugged terrain, including vast stretches of the Chihuahuan Desert and the Rio Grande river.

4. The first recorded tornado in Texas history occurred on May 21, 1884, in Lampasas County. While tornadoes are a relatively common occurrence in the state, this event was notable as it marked the first time that a tornado had been officially recorded and documented in the state's meteorological history.

5. On May 21, 2005, an EF3 tornado devastated the town of Quanah, Texas, causing significant damage to homes and businesses throughout the area. While tornadoes are a reality of life in Texas, this event was particularly destructive, demonstrating the scale of the damage that these extreme weather events can cause.