Oso's Slide Hill

Building toward disaster

The decades preceding the deadly landslide near Oso reflect a shifting landscape with one human constant: Even as warnings mounted, people kept moving in. This interactive graphic tells that story, starting in 1887. Thirteen aerial photographs from the 1930s on capture the geographical changes; the hill is scarred by a succession of major slides while the river at its base gets pushed away, only to fight its way back. This graphic lets you go back in time and track the warnings from scientists; the failed attempts to stabilize the hill; the logging on or near the unstable slope; and the 37 homes that were built below the hill only to be destroyed.

Scroll the timeline to see aerial photos and changes in the landscape over time.
Red Flags
Attempted Fixes



    This graphic relied on reports, memos, correspondence and photos obtained from local, state and federal agencies, including:

    Most of these records were obtained under the state’s Public Records Act or the U.S. Freedom of Information Act, or from the Washington State Archives.

    Some reporting relied on mapping and geographical analysis; among other steps we cross-referenced aerial photos and utilized lidar imagery, which exposes landscape beneath vegetation. In three instances – 1947, 1955 and 1969 – we needed to combine two aerial images taken on the same day, which is why there’s a visible line or divider toward the top of the photos.

    We researched newspaper archives and tapped books, videos and oral or written histories from people who studied the hill or lived in or visited this river valley. We also drew on news accounts from The Seattle Times, The (Everett) Herald and NBC News.


    Reporters: Ken Armstrong, Justin Mayo, Mike Baker and Jim Brunner
    Interactive: Thomas Wilburn
    Graphics: Mark Nowlin
    Editor: Beth Kaiman