Usually around 18" - 30", they can grow longer than 36".  One of the most common snakes I find here, especially when night driving.  I've never had any bite me, but they do musk and wriggle a bit.  They eat lizards, rodents,  sometimes other snakes, and reptile eggs.  A friend had one that ate thawed pinkies a few nights after capture.  They are found throughout most of Eddy county, usually avoiding the mountainous area.  All but one I have found looked like the above picture.  I had found a neonate that had very little red and looked like a banded California kingsnake.

                            
 
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 Range
 Expected Range