[genericuser314]

I think in any scenario where "nuclear war destroys a large portion of highways and communication equipment" then Houston, Dallas, San Antonio, and Austin will all be smoking craters.

Here's the 1990 FEMA assessment of nuclear targets in Texas: https://www.webpal.org/SAFE/state/TX/tx_nuclear.htm

Assuming that's accurate, my guess is that Odessa/Midland and Laredo would be Texas's major population centers.