The Cooper River is a mainly tidal river in the U.S. state of South Carolina. The South Carolina cities of Mt. Pleasant, Charleston, North Charleston, Goose Creek, Moncks Corner, and Hanahan are located along the river. Short and wide, it is joined first by the blackwater East Branch, then farther downstream, the tidal Wando River. Almost immediately thereafter, the river widens into its estuary, uniting with the Ashley River to form the Charleston Harbor.