Pantex is in Amarillo. That's considered West Texas.
North Texas is generally the Dallas/Ft. Area and north to the OK border.
Wichita Falls is nominally "West Texas", although some might consider otherwise. Abilene is definitely West Texas. In the other direction, Tyler is "East Texas".
I lived in Amarillo. If we wanted to go anywhere else significant in Texas (sorry, Dumas), we went south.
Then WTF is El Paso? I can hardly wait for the responses on that question! LOL!!!
I lived in El Paso for about 15 years. During one drive back to Dallas, I saw a sign in Baird (near Abilene) that said "Welcome to the Heart of West Texas!"
You can imagine my thoughts after driving for seven hours!