Nelson's milksnake ("Lampropeltis triangulum nelsoni") is a subspecies of king snake that is found in Mexico from southern Guanajuato and central Jalisco to the Pacific Coast. It is also found on the narrow plains of northwestern Michoacán and on the Tres Marias Islands. The range of this snake appears to be tied to the proximity of watercourses, including ones utilized for irrigation and agriculture. It is a subspecies of the milksnake, "Lampropeltis triangulum". It is similar in size to other king snakes, averaging long, and like them, is nonvenomous.