Previously, seven other C. viridis subspecies were also recognized, including C. v. abyssus, C. v. caliginis, C. v. cerberus, C. v. concolor, C. v. helleri, C. v. lutosus and C. v. oreganus.

However, in 2001 Ashton and de Queiroz described their analysis of the variation of mitochondrial DNA across the range of this species.

In Montana, specimens occasionally exceed 120 centimetres (3.9 ft) in length; the species reaches its maximum size in this region.

[9] Prairie rattlesnakes are found in North America over much of the Great Plains, the eastern foothills and some intermontane valleys of the Rocky Mountains, from southwestern Canada through the United States to northern Mexico.

In Canada, they occur in Alberta and Saskatchewan; in the US in eastern Idaho, most of Montana, North Dakota, South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, Texas, New Mexico, northeastern Arizona, extreme western Iowa, and in Mexico in northern Coahuila and northwestern Chihuahua.

[13] The venom of the Prairie rattlesnake is a complexly structured mixture of different proteins with enzymes such as proteases and peptidases found among them.

The average number of young ranges from four to 12, but can vary greatly due to availability of food and environmental conditions.

[16] They give birth in late summer or early fall, being their breed 22–28 cm long, without the need for parental care.

It is also common for females to give birth at communal den sites with the young born between August and October.

[1] Crotalus viridis nuntius Klauber, 1935,[3] the Hopi rattlesnake, inhabits the United States from northeastern and north-central Arizona, from the New Mexico border to Cataract Creek, including the Little Colorado River basin, the southern section of the Apache Indian Reservation, the Hopi Reservation, and the Coconino Plateau from the southern rim of the Grand Canyon to US Highway 66 in the south.

[10] Crotalus viridis viridis (Rafinesque, 1818),[3] the prairie rattlesnake, inhabits the North American Great Plains from the Rocky Mountains to 96° W and from southern Canada to extreme northern Mexico, including southwestern Saskatchewan, southeastern Alberta, eastern Washington, Idaho in the Lemhi Valley, Montana east of the higher Rockies, southwestern North Dakota, west, central and extreme southeastern South Dakota, western Iowa, central and western Nebraska, Wyoming except for the Rockies, Colorado, central and western Kansas, Oklahoma, extreme southeastern Utah, northeastern Arizona, New Mexico, western and southwestern Texas, northeastern Sonora, northern Chihuahua, northern Coahuila.