The Smith River is a river on the Pacific coast of northern California in the United States, approximately 20 mi (32 km) long. It drains a rugged area of the Pacific Coast Ranges west of the Siskiyou Mountains just south of the Oregon border and north of the watershed of the Klamath River. It is the largest river system in California that flows freely along its entire course. It was named for the explorer Jedediah Smith. It is sometimes known as the Smiths River.