Water moccasins, also called cottonmouths, live across the southeastern United States, from Virginia to Texas. Their range covers roughly 16 states, and they stick close to freshwater habitats like swamps, rivers, lakes, and floodplains. But they’re more versatile than most people realize, turning up in brackish coastal marshes, drainage ditches, and even suburban stormwater ponds.
Geographic Range by Region
Water moccasins are divided into three regional groups, each covering a distinct slice of the Southeast. The eastern cottonmouth ranges from southeastern Virginia through the Carolinas and into Georgia. The Florida cottonmouth lives throughout Florida, including the upper Keys, and extends into extreme southeastern Georgia. The western cottonmouth has the broadest range, stretching from eastern Texas and Oklahoma through Louisiana, Arkansas, Mississippi, and Alabama, then north into southern Missouri, western Tennessee and Kentucky, and the southern tips of Illinois and Indiana.
Where these regional populations meet, particularly across Alabama, parts of Mississippi, Georgia, South Carolina, and the western Florida panhandle, the lines blur and the groups intergrade.
The full list of states with native water moccasin populations: Virginia, North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, Texas, Oklahoma, Arkansas, Missouri, Tennessee, Kentucky, Illinois, Indiana, and Kansas (though Kansas has only a tiny population in the eastern corner of Cherokee County).
Northern and Western Boundaries
Water moccasins are a warm-climate species, and their range drops off sharply as you move north or west. In Missouri, no natural populations exist north of the Missouri River. In Illinois and Indiana, they’re limited to the extreme southern portions of each state. Virginia marks the northeastern edge of their range, and only the southeastern part of the state has established populations. In Kansas, they barely cross the border. West of central Texas, they’re absent entirely.
If you live north of roughly the 38th parallel (the latitude of southern Illinois) or in the arid Southwest, water moccasins are not part of your local wildlife.
Freshwater Habitats They Prefer
Water moccasins are almost always found near water. Their core habitats include swamps, wetlands, lakes, river bottoms, lowland floodplains, and slow-moving streams. Cypress swamps and delta bayous are classic cottonmouth territory. They also use sloughs, ponds, and seasonal floodplains during warmer months.
You’ll often spot them basking along the water’s edge, stretched out on logs, banks, or low-hanging vegetation near the shoreline. Unlike many nonvenomous water snakes, which regularly climb several feet up into tree branches to bask, cottonmouths seldom go high into trees. If you see a snake coiled on a branch well above the water, it’s more likely a harmless water snake than a moccasin.
Coastal and Brackish Environments
Water moccasins aren’t strictly freshwater snakes. They tolerate salt to a surprising degree, inhabiting brackish waters, tidal stream courses, salt marshes, and even offshore keys in Florida. Coastal dune and beach areas also fall within their range. This means that in states like Florida, Louisiana, and the Carolinas, cottonmouths can show up in habitats you might not associate with a “freshwater” snake, including tidal creeks and barrier island marshes.
Man-Made and Suburban Water Features
Cottonmouths readily colonize human-altered landscapes. Drainage ditches, retention ponds, stormwater ponds, and canal systems all provide the combination of water, cover, and prey (fish, frogs, small mammals, insects) that these snakes need. In South Carolina, the cottonmouth is one of only two venomous species that consistently lives near water, and stormwater ponds in suburban developments can attract them just as effectively as a natural wetland.
This is why homeowners in the southeastern U.S. sometimes encounter cottonmouths in backyard ponds, golf course water features, or neighborhood retention basins. The snake doesn’t distinguish between a natural swamp and a well-stocked suburban pond. If the habitat provides food, water, and hiding spots, cottonmouths may move in.
Where They Go in Winter
During cold months, water moccasins leave their aquatic habitats and move to sheltered overwintering sites. They brumate (the reptile equivalent of hibernation) underground, often on rocky wooded hillsides, inside crayfish burrows, beneath rotting stumps, or in abandoned mammal burrows. These winter sites can be some distance from water, which means cottonmouths occasionally turn up in drier, more wooded areas during fall and early spring as they travel to and from their cold-weather shelters.
They become inactive once temperatures drop consistently and are most active at night during the warmer months. In the Deep South, their active season is longer, sometimes nearly year-round in Florida, while populations at the northern edge of their range may brumate for four or five months.
Overlap With Nonvenomous Water Snakes
One reason people ask where water moccasins live is that they’re trying to figure out whether the snake they saw near water was actually a cottonmouth. The challenge: nonvenomous water snakes in the genus Nerodia share almost identical habitats. Both are found near water, eat the same prey, and bask in the same spots along shorelines and on logs.
Geography is your first filter. If you’re in Michigan, Pennsylvania, or anywhere outside the southeastern range described above, the water snake you saw is not a cottonmouth, no matter how thick-bodied or dark-colored it looks. Within the cottonmouth’s range, telling them apart requires looking at head shape, body posture, and behavior rather than habitat alone, since both species use the same waterways.