funding shortfalls. The state legislature approved funds for the extension of SSH 1R into the national forest, which began in late 1959. The SSH 1R designation was extended onto the new timberline highway, which opened to traffic on September 29, 1962. During the 1964 state highway renumbering, SSH 1R was designated SR 504 under the modern "sign route" (now state route) system. The state highway department completed construction of a new bridge over the Toutle River at Kid Valley in November 1965, replacing a narrower truss bridge. By the 1970s, several new campgrounds, trailheads, and recreation areas had been established along the highway by the Forest Service and logging companies like Weyerhauser to serve tourists visiting the Mount St. Helens area. A major flood in December 1977 left eight sections of the highway washed out and only passable by one lane of traffic until repairs were completed the following year. 1980 eruption and rebuilding In March 1980, Mount St. Helens was struck by an earthquake swarm that indicated potential eruptive activity for the volcano, which had been dormant for over a century. The Forest Service established a roadblock on SR 504 approximately west of Spirit Lake on March 28 because of potential avalanche risks. In the following days, the roadblock was moved to west of the lake and later west as the risk of an imminent eruption grew. Many local residents and sightseers violated the roadblock, which was planned to be moved further west by an order from Governor Dixy Lee Ray to take effect on May 19. An exception was made on May 17, allowing for the retrieval of belongings from various buildings during a four-hour period that was monitored by local authorities in case of a mass evacuation. On May 18, 1980, the north face of Mount St. Helens slid away and triggered a massive eruption that created a lahar that devastated the North Fork Toutle River. The lahar destroyed about of SR 504, including seven of the highway's eight major bridges, leaving only the Kid Valley bridge standing because of its sufficient clearance. The remaining section between Toutle and Kid Valley was buried in up to of sediment, but was able to re-open by September with temporary Bailey bridges and other structures. Several vehicles on the highway were swept away by the lahar, including those carrying some of the eruption's 57 victims. The highway was closed beyond