The Mini AADA RASG in GURPS Autoduel Second Edition has a small amount of information on Arizona, New Mexico, and Nevada.
High Velocity Duelling (HVD) was scheduled to publish the HVD Unofficial Guide to the Desert Southwest around 2000 or 2001, but that project was cancelled when HVD folded.
Earlier this month I uploaded once again the two HVD Arena Supplements to my Web site: Flashfire Circuit and Hot Asphalt Circuit.
Flashfire Circuit is a collection of arenas in the Midwest and Mountain West. Hot Asphalt Circuit is a collection of arenas in the Desert Southwest.
HVD Publications - Flashfire Circuit
http://www.seanet.com/~owenmp/hvd-ffac/index.html
HVD Publications - Hot Asphalt Circuit
http://www.seanet.com/~owenmp/hvd-hac/index.html