 Its habitat range overlaps with that of the common garter snake ("Thamnophis sirtalis") in many areas, and it is thought the two species may hybridize.The snake ranges across a broad area of North America from as far north as central Alberta to as far south as Northern Texas and New Mexico.In the United States, it is also found in Iowa, eastern Wyoming, northern Kentucky, eastern Colorado, Minnesota, southern Wisconsin, Illinois, northwestern Indiana, Oklahoma, Nebraska and the northern half of Missouri.