The department consists of mostly flat low-lying land through which flows the River Loire. This river enters the department near Châtillon-sur-Loire in the southeast, flows northwestwards to Orleans where it turns to flow south west, leaving the department near Beaugency. The Canal d'Orléans connects the Loire River at Orléans to a junction with the Canal du Loing and the Canal de Briare in the village of Buges near Montargis. The River Loire and these canals formed important trading routes before the arrival of the railways. The River Loiret, after which the department is named, is long and joins the Loire southwest of Orléans. Its source is at Orléans-la-Source, and its mouth at Saint-Hilaire-Saint-Mesmin. Other rivers in the department, are the River Loing, a right-bank tributary of the Loire, and the River Ouanne which flows into the Loing.