Here's all that is known about Texas:
http://fallout.wikia.com/wiki/Texas
The Texas Commonwealth actually included Arkansas, not Oklahoma.
Actually, now that you mention it texas WOULD be a good setting for a fallout game. Set it in fort worth! it would be cool to walk around the city i live in in a game....
Fallout: Brotherhood of Steel takes place in Texas, and the canceled Fallout: Brotherhood of Steel 2 was also going to be in Texas.