Not a huge fan of sports myself but I do know that here in Texas, it's a really big thing, especially college football (American football, or as some people call it, handegg). I lived in the Dallas area for most of my life and I currently attend UT Austin, and good grief are we serious about football even at a high school level. We've had vandalism between rival high schools where one school will dye another school's fountain maroon/blue/etc. among other things (graffiti was not uncommon, either).
Anyways, a lot of my friends and teachers pay attention to different teams. Some love basketball (myself included) and constantly root for the Mavericks. Others are really into football and talk about their love for the Cowboys. Actually, I don't know who didn't talk about the cowboys when football season started. I remember I had a music theory teacher who obsessed over the Rangers, and our lead violinist in orchestra admired the Stars.
As for myself, the only sports I ever follow are the Olympics, and I typically root for Team America and Team China, unless China and America are against each other. In which case it's always America first.