Although venomous (poisonous) snakes are relatively common in the U.S., bites from venomous snakes are a rare cause of death in this country. While there are about 8,000 venomous snake bites reported each year in the U.S., no more than 12 deaths were reported each year from 1960-1990 as a result of poisonous snake bites.
Pit vipers are a family of snakes whose scientific name is Crotalidae. This group, which is responsible for 99% of poisonous snake bites in the U.S., includes the rattlesnakes, copperheads, and water moccasins (cottonmouths). Within this group, rattlesnakes have the most deadly venom and cause the majority of snakebite-related deaths. Rattlesnakes can be found in both the Eastern and Western areas of the country. Copperheads, common in the Eastern U.S., have a milder venom than that of rattlesnakes. Water moccasins live around natural waters in the Southeast; their venom has an intermediate potency between that of the rattlesnakes and copperheads. Coral snakes found in the southern U.S., related to the Asian cobras and not part of the pit viper family, are a rare cause of poisonous snake bites in the U.S.