In October of 2009, a massive landslide in the Nile Valley, near Yakima, Washington, took out a portion of Washington SR 410 and impacted the Naches River as well. This video from WSDOT shows what emergency response was required to get temporary traffic restored on a detour and get a more permanent detour constructed.
Folks in Oregon are angry about a recent landslide and debris flow that closed Highway 30 and destroyed property in the town of Woodson. (Here is a powerpoint presentation by Bill Burns of the Oregon Department of Geology and Mineral Industries showing how the event happened). Some rather stinging allegations are being made that politicians withdrew a landslide hazard map from general use in 2002 for political reasons. That map or another one had characterized the area effected by the December 2007 debris flow as a "very high" or "extreme" risk of landslides. A very interesting article.