High Quality Content by WIKIPEDIA articles! The Snohomish County Centennial Trail is a rail trail in Snohomish County, Washington. It is a hard-surfaced, non-motorized trail for walking, bicycling, hiking, and horseback riding located on the Seattle, Lake Shore and Eastern Railway right-of-way, a route used until 1987. It is accessible to persons of all levels of physical ability. The trail is administered by Snohomish Parks and Recreation.It runs over 17 miles (27 km).