Common loons breed or occur in these states:
Alaska, Colorado, Connecticut, Delaware, Idaho, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Montana, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming.
They favor clear, fish-rich lakes in forested northern regions; winter on coastal waters.