Foreshadowing the spread across Montana? CWD was first diagnosed in southeastern Wyoming (marked in yellow) and over the last three decades has expanded in deer herds. The disease, in November 2017, was diagnosed for the first time ever in Montana wildlife just north of the state border with Wyoming and is now racing toward the heart of the Greater Yellowstone Ecosystem. Imagine this map flipped sideways to indicate a possible progression northward into Montana. “I see no reason not to believe that CWD will not advance through Montana as quickly it has through Wyoming,” says Lloyd Dorsey, hunter and conservation director for the Wyoming state chapter of the Sierra Club.