Hispanics mostly. One of the only cities in American that have a majority Hispanic population. And to let you know, I am Spanish, from San Antonio, and my family has lived in Texas for 400 years.
Go to Alamo Heights, Castle Hills, and going out to Hill Country etc. I know white population, it's mostly republican. Most of the Military population, Republican. It's not entirely blue. It's just b/c of the high Hispanic population is why it has been mostly voted democratic over the past couple of decades. But it use to be more Republican. This article does an excellent job of breaking up the demographics of San Antonio.
http://www.expressnews.com/news/loca...n-10605148.php