In Canada, the rattlesnakes are found in the extreme southern part of the country. The northern Pacific rattlesnake (Crotalus oreganus oreganus) is found in southern British Columbia. To the east, the prairie rattlesnake (Crotalus viridis) is found in southern Alberta and Saskatchewan. In eastern Canada, only the eastern massasauga (Sistrurus catenatus) and possibly the timber rattlesnake (Crotalus horridus) are found in southern Ontario.

The rattlesnakes are found almost throughout the entire United States only being absent from the extreme north-central part of the country.

In Latin America, the rattlesnakes are found throughout Mexico including Baja California and nearby islands, south through much of Central America although there seems to be a possible barrier between the North American species and those in South America in Panama where no rattlesnakes occur. Mexico enjoys the largest diversity of rattlesnakes from the large neotropical rattlesnakes (Crotalus durissus) and western diamondback rattlesnakes (Crotalus atrox) to the abundant numbers of smaller montane species.

Rattlesnakes are found through the northern two-thirds of the South American continent with exception of the Andes mountains and the Amazon Rainforest Basin. They can be found as far south as northern Argentina. In Brazil, the neotropical rattlesnake avoids the wet rainforest for the most part. In areas where it is in the rainforest, it is usually restricted to the drier patches of terrain located between tree stands.