With its western extreme in southeastern Arizona, the Massasauga is found through many of the midwestern states and is present as far east as portions of New York and adjacent Canada. Small, peripheral populations can also be found in northern Mexico. In Texas, S. c. edwardsii is present in south Texas, as well as northern portions of the Trans-Pecos and the Permian Basin region. Sistrurus c. tergeminus is found in the remaining vestiges of prairie along the Gulf Coast, central Texas, and the eastern Panhandle. Sistrurus catenatus edwardsii in blue Sistrurus catenatus tergeminus in green This project funded by the University of Texas College of Natural Sciences and the Texas Memorial Museum .
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