1. On April 20, 1836, the Battle of San Jacinto occurred in present-day Houston, Texas. This battle marked the final confrontation of the Texas Revolution, leading to Mexico's recognition of Texas as an independent country.

2. The first recorded tornado in Texas history struck on April 20, 1866, in the town of Brenham. The tornado caused widespread damage and resulted in the deaths of several residents.

3. In 1933, on April 20, the Texas Board of Education agreed to allow cowboy boots to be worn by male students in Texas schools. This decision recognized the importance of western culture and traditions to Texan identity.

4. On April 20, 1985, in Fort Worth, Texas, a tornado outbreak occurred. This event produced 19 tornadoes, resulting in significant damage and loss of life. The outbreak is considered one of the worst tornado outbreaks in Texas history.

5. April 20, 1999, was marked by the tragic shooting at Columbine High School in Colorado, but it also marks the date of the opening of the Lyndon B. Johnson Presidential Library in Austin, Texas. The library houses a collection of over 45 million pages of historical documents related to President Johnson's term in office.