U.S. Routes
... that U.S. Routes within Washington state currently make up about 1,800 miles (2,900 km) of the Washington highway system?
... that <b id="mwA4Y"><a href="./List_of_U.S._Routes_in_Washington" id="mwA4c" rel="mw:WikiLink" title="List of U.S. Routes in Washington">U.S. Routes</a></b> within <a class="mw-disambig" href="./Washington" id="mwA4g" rel="mw:WikiLink" title="Washington">Washington</a> state currently make up about <span about="#mwt16" data-mw='{"parts":[{"template":{"target":{"wt":"convert","href":"./Template:Convert"},"params":{"1":{"wt":"1800"},"2":{"wt":"mi"}},"i":0}}]}' id="mwA4k" typeof="mw:Transclusion">1,800 miles (2,900</span><span about="#mwt16" typeof="mw:Entity"> </span><span about="#mwt16">km)</span> of the <a href="./State_highways_in_Washington" id="mwA4o" rel="mw:WikiLink" title="State highways in Washington">Washington highway system</a>?