The Mountains to Sound Greenway stretches over 100 miles along Interstate 90 from the shores of Puget Sound in Seattle, over Snoqualmie Pass and into Central Washington. Much of the Greenway is public land and includes over 700,000 acres held by local, state and federal agencies in trust for the public good. The Greenway includes whitewater resources of national significance just outside the Seattle metropolitan area. American Whitewater is a partner with the Greenway in developing a longterm vision for the protection and stewardship of these whitewater rivers, many of which have been determined by the Forest Service to be eligible for Wild and Scenic designation.

American Whitewater served in a leadership capacity to designate the Mountains to Sound Greenway as a National Heritage Area in 2019 (Public Law 116-9).