September 7 in San Antonio history…

1884
The Post Office in Kendalia in Kendall County is held up in daylight by two Winchester-wielding bandits.  Net take was 75 cents.

1921
Rain begins to fall in San Antonio and will continue for three days leading to widespread flooding, killing 51 people and causing millions of dollars in damages. The flood was caused by some of the heaviest rainfall ever recorded in Texas. The immense amount of rain quickly overwhelms the the San Antonio River. Five to 10 feet of water submerged the city’s streets, delaying an evacuation.  The city was underwater for nearly a week following the flood, which was responsible for at least $5 million in damages. In the aftermath, San Antonio embarked on a 10-year overhaul of its flood system.

1972
The first Folklife Festival opens on the grounds of the Institute of Texan Cultures. 7,546 people attend on opening day.