San Antonio was a city in in the state of Texas in the nation-state of the United States of America on Earth.
The Battle of the Alamo took place at the Alamo mission in San Antonio in 1836. (DS9: "Badda-Bing, Badda-Bang", "What You Leave Behind")
In the Dixon Hill series of holonovels, the mother of Madeline, Dixon Hill's secretary, had a female cousin that lived in San Antonio. (TNG: "Manhunt")