Overall, it is probably the second largest-bodied species of rattlesnake, behind only its close cousin the eastern diamondback rattlesnake, and is also the second largest of North American venomous snakes (the bushmasters, which attain probably similar weights and greater total length, occur up as far as Nicaragua). Males become much larger than females, with ddults commonly growing to 4 ft in length. Specimens over 5 ft are infrequently encountered, while those over 180 cm (6 ft) are very rare.
It is likely responsible for the majority of snakebite fatalities in northern Mexico and the greatest number of snakebites in the U.S.
