The Calumet Region is the geographic area drained by the Grand Calumet River and the Little Calumet River of northeastern Illinois and northwestern Indiana in the United States. It is part of the Great Lakes Basin, which eventually reaches the Atlantic Ocean. It is a sub-region of the greater Northwest Indiana region and the even larger Great Lakes region. This region includes the northern parts of Lake and Porter counties and the western portion of La Porte county in Indiana, as well as the eastern counties of northern Illinois, Will and Cook.