The Songkhram River is a tributary of the Mekong River. It originates in the hills between Nong Han District, Udon Thani Province and Sawang Daen Din District, Sakon Nakhon Province. It flows through Seka District, Wanon Niwat, and Si Songkhram District and empties into the Mekong River in tambon Chai Buri, Tha Uthen District, Nakhon Phanom Province. It is 420 kilometres (260 mi) long.