Amarillo is another Texas town that I visit on a semi regular basis, and there are only 2 types of restaurants that will make money there...steak houses and Mexican restaurants. I don't know what the census data looks like, but every time I'm there it looks to be split down the middle with cowboys and Mexicans.
By the way if you ever end up in Amarillo this place rocks
http://bigtexan.com/. I've never tried the 72 ounce steak challenge but the food is amazing...