Texas is large & we have specific regions & sub-regions due to terrain variations (I haven't listed all regions and sub-regions).
We say:
West Texas (Anything West of IH-35)
North Texas (Anything North of Waco)
East Texas (Anything an hour East of IH-35 or farther)
South Texas (Anything South of New Braunfels)
The Panhandle (Self-explanatory)
The Gulf Coast (Texas Coastline)
Sub-regions:
The Real South (Anything South of Corpus Christi)
The Hill Country (An area that is South of Waco, North of Poteet, East of Manor, West of Bastrop = Austin, San Marcos, Round Rock, Lampasas, Kerrville, Boerne, North San Antonio, Fredericksburg, etc)
The Border/RGV/The Valley (Self-explanatory)
The Piney Woods (Deep East Texas, near the Louisiana border)
Big Bend/El Paso (The El Paso area)