The problem I have with the NM milksnakes is that they are so variable throughout their range. Snakes from areas around Albuquerque are very different than snakes from western Texas.
Many NM milksnakes in captivity actually come from west Texas, particularly the Davis Mts and the River Road. Most of the Davis Mountain snakes are very annulata like in my experience. The river road snakes are smaller and paler, but very pretty.
The same is true for annulata. Most annulata in captivity probably originate from one of two roads near the town of Freer. Some populations neared the coast are smaller and show LA milksnake intergradation (and aren't as pretty). For really nice annulata, you have to get further southwest (the ones in north eastern Mexico are really nice!).
Here's a female from near Hebbronville, TX.

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Chris Harrison