Concord lies fully within the Merrimack River watershed, and is centered on the river, which runs from northwest to southeast through the city. Downtown is located on a low terrace to the west of the river, with residential neighborhoods climbing hills to the west and extending southwards towards the town of Bow. To the east of the Merrimack, atop a bluff, is a flat, sandy plain known as Concord Heights, which has seen most of the city's commercial development since 1960. The eastern boundary of Concord (with the town of Pembroke) is formed by the Soucook River, a tributary of the Merrimack. The Turkey River winds through the southwestern quarter of the city, passing through the campus of St. Paul's School before entering the Merrimack River in Bow. In the northern part of the city, the Contoocook River enters the Merrimack at the village of Penacook.