The river otter historically occurred over much of the North American continent. River otters have been extirpated or are rare in Arizona, Colorado, Indiana, Iowa, Kansas, Kentucky, Nebraska, New Mexico, North Dakota, Ohio, Oklahoma, South Dakota, Tennessee, Utah, and West Virginia. They are still relatively abundant along the coasts of the Atlantic Ocean and the Gulf of Mexico, throughout the Pacific Northwest and Great Lakes states, and across most of Canada and Alaska.
River otters inhabit a variety of riparian plant communities.