List of former state routes in Washington
Since the 1964 state highway renumbering, which established the current state route system, the Washington State Department of Transportation has decommissioned some state routes. Once a highway has been decommissioned, the highway is turned over to the local county or city that it is in, they are then responsible for all maintenance on the former highway. All former highways are codified in Washington law under the Revised Code of Washington, chapter 47.17, section 420.
Source: Wikipedia
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