The Snohomish River is a river in Snohomish County, Washington, formed by the confluence of the Skykomish and Snoqualmie rivers near Monroe. It flows northwest entering Port Gardner Bay, part of Puget Sound, between Everett and Marysville. The Pilchuck River is its main tributary and joins the river at Snohomish. The river system drains the west side of the Cascade Mountains from Snoqualmie Pass to north of Stevens Pass.

The Skykomish River is a 29-mile (47 km) long river in the U.S. state of Washington which drains the west side of the Cascade Mountains in the southeast section of Snohomish County and the northeast corner of King County. The river starts with the confluence of the North Fork Skykomish River and South Fork Skykomish River approximately one mile west of Index, then flowing northwesterly towards Puget Sound. It is joined by the Sultan River and the Wallace River at Sultan. It then meets the Snoqualmie River to form the Snohomish River at Monroe. The Snohomish River continues along the river valley eventually dumping into Port Gardner Bay on Possession Sound.