:Washington State Route 504

File:Hoffstadt Creek Bridge.JPG|alt=A steel bridge with a slight arch, carrying a two-lane road across a gorge that cuts between grasslands with small trees.]]

SR 504 begins as an extension of Huntington Avenue at an interchange with I-5 northeast of Castle Rock. The street continues southwest into downtown Castle Rock as SR 411 and I-5 Business. SR 504 travels northeasterly through a small commercial area before ascending into the hills above Salmon Creek, passing several farms and wineries along the way.{{cite news |date=June 20, 2012 |title=Multi-venue exhibit toasts fine wine, art |url=https://tdn.com/lifestyles/multi-venue-exhibit-toasts-fine-wine-art/article_58305116-bbc6-11e1-a7b5-0019bb2963f4.html |work=The Daily News |location=Longview, Washington |access-date=August 29, 2018}} The highway follows a minor stream heading southeast into the wetlands around Silver Lake, where the Mount St. Helens visitor center and Seaquest State Park lie.{{cite web |date=April 2, 2018 |title=Corridor Sketch Summary – SR 504: I-5 Jct to Johnston Ridge |url=https://www.wsdot.wa.gov/sites/default/files/2017/08/25/CSS329-SR504-i5Jct-JohnstonRidge.pdf |publisher=Washington State Department of Transportation |access-date=August 29, 2018}}{{cite news |last=Hewitt |first=Scott |date=May 13, 2016 |title=Mount St. Helens visitors centers are a blast |url=https://www.columbian.com/news/2016/may/13/mount-st-helens-visitors-centers-open/ |work=The Columbian |access-date=August 29, 2018}} SR 504 continues along the north side of the lake and passes through the town of Toutle at the confluence of the Toutle River's two forks.{{google maps |title=State Route 504 |url=https://www.google.com/maps/dir/46.2845652,-122.9026927/46.2765866,-122.216705/@46.3270787,-122.6897422,11z/am=t/data=!3m1!4b1!4m2!4m1!3e0 |access-date=August 26, 2018}}

The highway crosses over the river on the Coal Bank Bridge and continues along the north side of the North Fork Toutle River, following the narrow valley to the east of Beigle Mountain. Near the Riverdale Raceway, SR 504 intersects the east end of SR 505, which provides connections to I-5 and Toledo.{{cite web |date=April 2, 2018 |title=Corridor Sketch Summary – SR 505: SR 603 Jct (Winlock) to SR 504 Jct |url=https://www.wsdot.wa.gov/sites/default/files/2017/09/18/CSS330-SR505-SR603JctWinlock-SR504Jct.pdf |publisher=Washington State Department of Transportation |access-date=August 29, 2018}} The highway continues northeast into Kid Valley, home to camping sites and a few homes,{{cite news |last=Goldstein |first=Steve |date=February 26, 2006 |title=Back to the blast |page=N1 |work=Philadelphia Inquirer |url=https://www.newspapers.com/clip/23274385/mount_st_helens_guide_2006/ |via=Newspapers.com |access-date=August 29, 2018}} and follows the south side of the narrower valley as the river meanders north and south around various mountains.{{cite web |date=July 2018 |title=Washington State's Scenic Byways & Road Trips |pages=78–79 |url=https://www.wsdot.wa.gov/sites/default/files/2018/07/17/scenic-byways-travel-planner.pdf |publisher=Washington State Department of Transportation |access-date=August 30, 2018 |archive-date=July 15, 2020 |archive-url=https://web.archive.org/web/20200715195433/https://www.wsdot.wa.gov/sites/default/files/2018/07/17/scenic-byways-travel-planner.pdf |url-status=dead }} At a third crossing of the river, SR 504 intersects a short spur route on Sediment Dam Road that leads to a viewpoint overlooking the Toutle River Sediment Dam. The highway continues along the northeast side of the earthen dam and its reservoir, climbing uphill and running through cuts in the cliffs.{{cite news |last=Robinson |first=Erik |date=May 15, 2005 |title=Along Highway 504 |page=35 |work=The Columbian |url=https://www.newspapers.com/article/the-columbian-along-highway-504/131068039/ |via=Newspapers.com |accessdate=September 1, 2023}}

Further southeast along the river, SR 504 passes the privately owned Eco Park resort, a youth camp, and a heliport near the Hoffstadt Bluffs Viewpoint.{{cite news |last=Anderson |first=Rick |date=January 7, 2018 |title=Nearly four decades after Mt. St. Helens erupted, a resort in the blast zone faces a different kind of danger |url=http://www.latimes.com/nation/la-na-washington-volcano-danger-2018-story.html |work=Los Angeles Times |access-date=August 28, 2018}}{{cite news |last=Norimine |first=Hayat |date=January 10, 2017 |title=County sells Hoffstadt Bluffs Visitor Center for summer kids camp |url=https://tdn.com/news/local/county-sells-hoffstadt-bluffs-visitor-center-for-summer-kids-camp/article_57e2f4da-1e79-5ab8-9f45-f012dba44bb9.html |work=The Daily News |location=Longview, Washington |access-date=August 28, 2018}} The highway then crosses over Hoffstadt Creek on a {{convert|2,340|ft|m|adj=mid}} steel truss bridge that sits {{convert|370|ft|m}} above the valley floor; it is the longest of 13 bridges on SR 504.{{cite web |author=Bridge and Structures Office |date=November 2017 |title=Bridge List (M 23-09.08)

|page=299 |url=https://www.wsdot.wa.gov/publications/manuals/fulltext/M23-09/BridgeList.pdf |publisher=Washington State Department of Transportation |access-date=August 30, 2018}}{{cite news |last=Patty |first=Stanton H. |date=May 13, 1990 |title=A new St. Helens road will honor a brave volcanologist |page=G15 |work=Dallas Morning News}} The bridge also marks the western extent of the "blast zone," where trees were felled during the 1980 eruption of Mount St. Helens, located {{convert|12|mi|km}} away.{{cite news |last=McDougall |first=Connie |date=November 11, 2004 |title=What a view: Fall colors and a frisky mountain |page=G26 |work=The Seattle Times |url=https://archive.seattletimes.com/archive/20041111/nwwsthelens11/mount-st-helens-fall-colors-and-a-frisky-mountain |access-date=August 30, 2018}}{{cite news |last=Hamm |first=Catharine |date=May 30, 2004 |title=Antiquer treasures a surprising discovery |page=L8 |work=Los Angeles Times |url=https://www.latimes.com/archives/la-xpm-2004-may-30-tr-centralia30-story.html |access-date=August 28, 2018}} The area has large forests of young fir, pine, and cottonwood trees planted by Weyerhaeuser in the 1980s as part of a regeneration and restoration project. The company also operates the Charles W. Bingham Forest Learning Center, a museum that overlooks the North Fork Toutle River and also includes a rest area.{{cite news |last=Parker |first=Pat |date=July 7, 2018 |title=Weyerhaeuser a hero at St. Helens |page=B7 |work=Enterprise-Journal |location=McComb, Mississippi |url=https://www.newspapers.com/clip/23274773/weyerhaeuser_a_hero_at_st_helens/ |via=Newspapers.com |access-date=August 30, 2018}}{{cite news |last=Gottberg Anderson |first=John |date=September 10, 2017 |title=Three sides of Mount St. Helens |url=https://www.bendbulletin.com/home/5575215-151/three-sides-of-mount-st-helens |work=Bend Bulletin |access-date=August 29, 2018}}

File:State Route 504 eastbound approaching Mount St. Helens near Castle Lake.jpg from the northwest]]

SR 504 continues further into the mountains, crossing Bear Creek and traveling around Elk Rock to a viewpoint on its southeast side. From the Elk Rock area, the highway forms the northern boundary of the Mount St. Helens National Volcanic Monument and encounters more mountainous terrain that results in several hairpin turns between other scenic viewpoints.{{cite map |date=June 2017 |title=Mount St. Helens National Volcanic Monument |url=https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprd3843447.pdf |publisher=United States Forest Service |access-date=August 30, 2018}} After crossing several branches of Maratta Creek, SR 504 reaches a partial cloverleaf interchange with an access road that serves the Coldwater Science and Learning Center, a visitor center that overlooks the mountain and open from autumn to spring. The highway heads west before completing a hairpin turn to travel south around the end of Coldwater Lake. Beyond milepost 45, SR 504 is closed during the winter months due to hazardous conditions for drivers and potential avalanches.{{cite news |date=December 24, 2002 |title=Weather closes portion of SR 504 |url=https://tdn.com/news/weather-closes-portion-of-sr/article_f925d5e4-50fc-52dd-9633-1e7720c9f8b9.html |work=The Daily News |location=Longview, Washington |access-date=August 30, 2018}} It typically reopens in time for the May 18 anniversary of the 1980 eruption.{{cite news |last=Fairbanks |first=Katie |date=May 3, 2023 |title=Road to Johnston Ridge now open, visitor center plans mid-May reopening |url=https://tdn.com/news/local/road-to-johnston-ridge-now-open-visitor-center-plans-mid-may-reopening/article_155d2aa0-e9e4-11ed-8623-03f07324b6d2.html |work=The Daily News |location=Longview, Washington |accessdate=May 16, 2023}}

The highway continues into the National Volcanic Monument and turns east before reaching the border between Cowlitz and Skamania counties. SR 504 follows South Coldwater Creek upstream through a narrow valley to its headwaters near Spirit Lake, passing several trailheads, and turns west to continue its ascent. The treeless landscape is home to winter herds of Rocky Mountain elk and deer.{{cite news |last=Richard |first=Terry |date=January 21, 1998 |title=Washington 504: A road for all seasons |page=D9 |work=The Oregonian}} The highway turns east once again near the Loowit Viewpoint and reaches the Johnston Ridge Observatory, the volcano's main visitor center open from spring to autumn and situated at an elevation of {{convert|4,314|ft|m}}. SR 504 terminates downhill from the observatory at its parking lot, located {{convert|5.5|mi|km}} north of the Mount St. Helens crater.{{cite news |last=Mapes |first=Lynda |date=May 13, 2010 |title=Recreation at Mount St. Helens, 30 years after the blast |page=D4 |url=http://old.seattletimes.com/html/outdoors/2011801593_nwwsthelens13.html |work=The Seattle Times |access-date=August 30, 2018}}{{cite news |last=Gottberg Anderson |first=John |date=August 5, 2007 |title=Hot spot of the Cascades |url=https://www.bendbulletin.com/slideshows/1523692-151/hot-spot-of-the-cascades |work=Bend Bulletin |access-date=August 30, 2018}}

SR 504 is maintained by the Washington State Department of Transportation (WSDOT), which conducts an annual survey on state highways to measure traffic volume in terms of annual average daily traffic. Average traffic volumes on the highway in 2016 ranged from a minimum of 500 vehicles near Coldwater Lake to a maximum of 14,000 vehicles at the I-5 interchange in Castle Rock.{{cite report |year=2017 |title=2016 Annual Traffic Report |pages=191–192 |url=http://www.wsdot.wa.gov/mapsdata/travel/pdf/Annual_Traffic_Report_2016.pdf |publisher=Washington State Department of Transportation |access-date=August 27, 2018 |archive-date=August 12, 2017 |archive-url=https://web.archive.org/web/20170812180326/http://www.wsdot.wa.gov/mapsdata/travel/pdf/Annual_Traffic_Report_2016.pdf |url-status=dead }} SR 504 is the main route for a majority of the 3 million annual visitors to the Mount St. Helens area.{{cite news |last=Richard |first=Terry |date=January 22, 2014 |title=Mount St. Helens welcomes winter weekend visitors at Coldwater as science center evolves |url=https://www.oregonlive.com/travel/index.ssf/2014/01/mount_st_helens_welcomes_winte.html |work=The Oregonian |access-date=August 30, 2018}}{{cite news |last=Richard |first=Terry |date=October 29, 2009 |title=Mount Margaret will get you going |url=http://blog.oregonlive.com/terryrichard/2008/09/mt_margaret_get_going.html |work=The Oregonian |access-date=August 30, 2018}} It is designated by the state government as the Spirit Lake Memorial Highway, a state scenic byway, and a National Forest Scenic Byway by the United States Forest Service.{{cite web |title=Spirit Lake Memorial Highway |url=http://byways.org/explore/byways/2237 |work=National Scenic Byways Online |publisher=Federal Highway Administration |url-status=dead |archive-url=https://web.archive.org/web/20130807224305/http://byways.org/explore/byways/2237 |archive-date=August 7, 2013 |access-date=August 30, 2018}}

The Spirit Lake Highway was completed in 1903 by the Cowlitz County government, connecting Castle Rock to the shore of Spirit Lake by following the North Fork Toutle River.{{cite book |last=Colasurdo |first=Christine |year=1997 |title=Return to Spirit Lake: Journey Through a Lost Landscape |page=44 |publisher=Sasquatch Books |location=Seattle |isbn=978-1570610813 |oclc=37004379 |url=https://books.google.com/books?id=pcdohfWwgo0C |via=Google Books |access-date=September 3, 2018}} The {{convert|47|mi|km|adj=on}} highway was initially unpaved and characterized as rough and narrow, and several sections were improved or bypassed in the 1910s.{{cite news |date=August 31, 1919 |title=Charles Menzies Says Spirit Lake Trip Delightful |page=10 |work=The Oregon Daily Journal |url=https://www.newspapers.com/clip/23303828/spirit_lake_highway_review_1919/ |via=Newspapers.com |access-date=September 4, 2018}} It was added to the state highway system in 1937 as Secondary State Highway 1R (SSH 1R), terminating at the western boundary of the Columbia National Forest near Spirit Lake.{{cite book |date=March 18, 1937 |title=Session Laws of the State of Washington, 1937 |chapter=Chapter 207: Classification of Public Highways |page=997 |chapter-url=http://leg.wa.gov/CodeReviser/documents/sessionlaw/1937c207.pdf |publisher=Washington State Legislature |access-date=September 4, 2018}} The state government paved sections of the highway in the late 1930s and early 1940s,{{cite news |date=November 22, 1931 |title=Spirit Lake Road Link Is Completed |page=30 |work=The Seattle Times}} with only a short section at the east end remaining unpaved by 1944.{{cite map |author=Rand McNally |year=1944 |title=Highways of the State of Washington |location=Olympia |publisher=Washington State Department of Highways |url=https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~290279~90061931 |via=David Rumsey Historical Map Collection |access-date=September 4, 2018}} The remaining section of the highway within Columbia National Forest was improved and paved by the federal Bureau of Public Roads in the late 1930s for $1.2 million (equivalent to ${{Format price|{{Inflation|US-GDP|1200000|1936}}}} in {{Inflation-year|US-GDP}} dollars).{{inflation-fn|US-GDP}}{{cite news |date=January 31, 1936 |title=Grading Plans Made for Road To Spirit Lake |page=3 |work=The Seattle Times |agency=Associated Press}}

Expanded logging and a planned ski resort on Mount St. Helens hastened the construction of a modern highway linking Spirit Lake to the timberline on the mountain's northern slopes in the 1950s.{{cite news |last=Hess |first=George |date=November 30, 1956 |title=All-Weather Road To Mt. St. Helens Timberline Asked |page=1 |work=Longview Daily News |url=https://www.newspapers.com/clip/42816235/allweather_road_to_mt_st_helens/ |via=Newspapers.com |access-date=January 22, 2020}}{{cite news |date=June 3, 1958 |title=Spirit Lake Work Favored |page=7 |work=The Daily Chronicle |url=https://www.newspapers.com/clip/23455486/spirit_lake_and_timberline_highway/ |via=Newspapers.com |access-date=September 4, 2018}} Despite support from the state government, the Forest Service, and Bureau of Public Roads, the highway project was put on hold for several years due to funding shortfalls.{{cite news |date=November 28, 1957 |title=Lack of Road Funds Cited |page=55 |work=The Seattle Times |agency=Associated Press}} The state legislature approved funds for the {{convert|5|mi|km|adj=mid|spell=in}} extension of SSH 1R into the national forest, which began in late 1959.{{cite news |date=May 5, 1959 |title=Road Link Wins Okeh |page=1 |work=The Daily Chronicle |url=https://www.newspapers.com/clip/23455478/spirit_lake_highway_extension/ |via=Newspapers.com |access-date=September 4, 2018}} The SSH 1R designation was extended onto the new timberline highway, which opened to traffic on September 29, 1962.{{cite book |date=April 3, 1961 |title=Session Laws of the State of Washington, 1961 extraordinary session |chapter=Chapter 21: Highways |page=2620 |chapter-url=http://leg.wa.gov/CodeReviser/documents/sessionlaw/1961ex1c21.pdf |publisher=Washington State Legislature |access-date=September 4, 2018}}{{cite news |date=September 28, 1962 |title=Timberline Road Dedication Set on Saturday Afternoon |page=9 |work=Longview Daily News |url=https://www.newspapers.com/clip/42816362/timberline_road_dedication_set_on/ |via=Newspapers.com |access-date=January 22, 2020}}

During the 1964 state highway renumbering, SSH 1R was designated SR 504 under the modern "sign route" (now state route) system.{{cite web |author=C. G. Prahl |date=December 1, 1965 |title=Identification of State Highways |url=https://www.wsdot.wa.gov/sites/default/files/2005/04/26/Identification-of-state-highways.pdf |publisher=Washington State Highway Commission |access-date=September 4, 2018 |archive-date=February 2, 2020 |archive-url=https://web.archive.org/web/20200202073838/https://www.wsdot.wa.gov/sites/default/files/2005/04/26/Identification-of-state-highways.pdf |url-status=dead }} 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.{{cite web |date=November 1965 |title=Official Opening, Kid Valley Bridge (Toutle River) |publisher=Washington State Department of Highways |url=https://cdm16977.contentdm.oclc.org/digital/collection/p16977coll3/id/562 |via=WSDOT Library Digital Collections |access-date=September 4, 2018}} 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.{{cite news |date=April 22, 1971 |title=Mount St. Helens recreation plans told |page=A1 |work=The Seattle Times |agency=Associated Press}}{{cite news |date=June 3, 1951 |title=Mt. St. Helens–Spirit Lake |page=10 |work=The Seattle Times}} 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.{{cite news |date=January 15, 1978 |title=Highway work put off |page=B15 |work=The Seattle Times}}

File:WA-504 St. Helens Bridge after 1980 eruption.jpg carrying SR 504 over the North Fork Toutle River that was destroyed by the May 1980 eruption's lahar|alt=A broken steel bridge sits in a pile of mud, with a person posing next to a section that is buried halfway]]

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.{{cite web |last=Lange |first=Greg |date=May 15, 2003 |title=Mount St. Helens erupts on May 18, 1980 |url=http://www.historylink.org/File/5457 |work=HistoryLink |access-date=September 6, 2018}} The Forest Service established a roadblock on SR 504 approximately {{convert|4|mi|km}} west of Spirit Lake on March 28 because of potential avalanche risks.{{cite news |last=Dardarian |first=Suki |date=March 27, 1980 |title=More quakes rock St. Helens; evacuation readied |page=B1 |work=The Seattle Times}} In the following days, the roadblock was moved to {{convert|15|mi|km}} west of the lake and later {{convert|30|mi|km}} west as the risk of an imminent eruption grew.{{cite news |last=Zahler |first=Richard |date=March 28, 1980 |title=Red Cross getting ready for evacuees |page=D3 |work=The Seattle Times}}{{cite news |date=March 29, 1980 |title=Mountain folk a bit uneasy now |page=A14 |work=The Seattle Times}} 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.{{cite news |date=May 14, 1981 |title=Safety questions head for courts |page=B2 |work=The Seattle Times}} 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.{{cite news |date=May 17, 1980 |title=St. Helens' cabin owners to defy state roadblock |page=A1 |work=The Seattle Times}}{{cite news |date=May 25, 1980 |title=Volcano: Day by day, the deadly pressure grew |page=B2 |work=The Seattle Times}}

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 {{convert|25|mi|km}} of SR 504, including seven of the highway's eight major bridges, leaving only the Kid Valley bridge standing because of its sufficient clearance.{{cite news |date=May 19, 1980 |title=Hot mud, ash carry havoc from St. Helens |page=A2 |work=The Seattle Times}}{{cite news |date=May 20, 1980 |title=Extent of devastation defies tally |page=A3 |work=The Seattle Times}}{{cite book |date=October 1985 |title=Mount St. Helens National Volcanic Monument Final Environmental Impact Statement Comprehensive Management Plan |page=111 |publisher=United States Forest Service |oclc=16695934 |url=https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fseprd500683.pdf |access-date=September 5, 2018}} The remaining section between Toutle and Kid Valley was buried in up to {{convert|6|ft|m|1}} of sediment, but was able to re-open by September with temporary Bailey bridges and other structures.{{cite journal |last1=Lombard |first1=R. E. |last2=Miles |first2=M. B. |last3=Nelson |first3=L. M. |last4=Kresh |first4=D. L. |last5=Carpenter |first5=P. J. |year=1981 |title=The impact of mudflows of May 18 on the Lower Toutle and Cowlitz rivers |pages=704–707 |journal=Geological Survey Professional Paper 1250: The 1980 Eruptions of Mount St. Helens, Washington |publisher=United States Geological Survey |lccn=81-600142 |url=https://books.google.com/books?id=9sZUAAAAYAAJ&pg=PA693 |via=Google Books |access-date=September 5, 2018}}{{cite news |date=August 25, 1980 |title=Firefighters take advantage of the lull around volcano |page=11 |work=Albany Democrat-Herald |url=https://www.newspapers.com/clip/23487126/lull_around_volcano/ |via=Newspapers.com |access-date=September 5, 2018}} Several vehicles on the highway were swept away by the lahar, including those carrying some of the eruption's 57 victims.{{cite news |date=May 25, 1980 |title=Eruption sends ash to Portland |page=A1 |work=The Seattle Times}}

File:Mudflow covering SR 504 near Coal Bank bridge, July 1980.jpg

The highway was closed beyond the town of Toutle, controlled by a roadblock and an existing turnaround loop installed by Weyerhaeuser.{{cite news |date=July 4, 1980 |title=Foreigners flock to volcano to see devastated landscape |page=A3 |work=Times-News |agency=United Press International |location=Twin Falls, Idaho |url=https://www.newspapers.com/clip/23631477/foreigners_flock_to_volcano_to_see/ |via=Newspapers.com |access-date=September 10, 2018}}{{cite news |date=June 5, 1980 |title=Blockade where some may have died was to be moved next day |page=B10 |work=The Seattle Times}} Access to Kid Valley was restored by early September using a temporary Bailey bridge over the Toutle River.{{cite news |date=August 27, 1980 |title=Volcano slopes spruced up |page=A10 |work=The Sentinel |location=Carlisle, Pennsylvania |agency=United Press International |url=https://www.newspapers.com/clip/23634666/volcano_slopes_spruced_up/ |via=Newspapers.com |access-date=September 11, 2018}} The highway was extended to the debris and sediment dam and Weyerhaeuser's Camp Baker site in 1987 at a cost of $11 million (equivalent to ${{Format price|{{Inflation|US-GDP|11000000|1987}}}} in {{Inflation-year|US-GDP}} dollars).{{inflation-fn|US-GDP}}{{cite news |date=May 6, 1981 |title=Washington prepares to cope with volcano tourist traffic |page=21 |work=Corvallis Gazette-Times |agency=Associated Press |url=https://www.newspapers.com/clip/23633181/washington_prepares_to_cope_with/ |via=Newspapers.com |access-date=September 11, 2018}}{{cite news |last=Gough |first=William |date=July 20, 1987 |title=Explosive changes rock quiet Toutle |page=C1 |work=The Seattle Times}} In 1982, the federal government designated the area around the volcano as the Mount St. Helens National Volcanic Monument and the state government designated SR 504 as the Spirit Lake Memorial Highway to honor the victims of the eruption.{{cite news |last=Richmond |first=Michael |date=August 8, 1985 |title=Mount St. Helens—five years later |page=C1 |work=Evening Tribune |location=San Diego}}{{cite book |date=March 27, 1982 |title=Session Laws of the State of Washington, 1982 |chapter=Chapter 82: Spirit Lake Memorial Highway |pages=412–413 |chapter-url=http://leg.wa.gov/CodeReviser/documents/sessionlaw/1982c82.pdf |publisher=Washington State Legislature |access-date=September 11, 2018}} A visitor center was also opened at Silver Lake in 1987 to serve the growing number of tourists to the area, but the highway would remain closed beyond the sediment dam.{{cite news |last=Hapala |first=Suzanne |date=March 29, 1987 |title=Re-setting sights on St. Helens |page=J1 |work=The Seattle Times}}{{cite news |last=Brown |first=J. D. |date=May 24, 1992 |title=Spirit Lake Memorial Highway |page=12 |url=https://www.nytimes.com/1992/05/24/travel/the-peak-that-sometimes-roars.html |work=The New York Times |access-date=September 11, 2018}}

Preliminary plans for a replacement for the highway to serve the north side of Mount St. Helens were approved by the state government in 1986. The highway would include {{convert|23|mi|km}} of new road built at a higher elevation between Kid Valley and the newly formed Coldwater Lake, crossing over various creeks with ten major bridges. The project's $118 million cost (equivalent to ${{Format price|{{Inflation|US-GDP|118000000|1986}}}} in {{Inflation-year|US-GDP}} dollars){{inflation-fn|US-GDP}} was paid from emergency funds from the Federal Highway Administration.{{cite news |last=Gough |first=William |date=October 1, 1986 |title=Going up: New highway will provide spectacular St. Helens view |page=A1 |work=The Seattle Times}}{{cite map |date=May 1989 |title=State Route 504 Spirit Lake Memorial Highway Reconstruction Projects |publisher=Washington State Department of Transportation |url=https://www.digitalarchives.wa.gov/Record/View/79CF4BB3F3A89EE99424A503BB45F2B1 |via=Washington State Archives |access-date=September 11, 2018}} Construction of the new highway and its scenic viewpoints began in 1988 and the first section to the Coldwater Ridge visitor center was completed on October 16, 1992.{{cite news |date=September 11, 1988 |title=Mount St. Helens road job under way |page=B2 |work=The Seattle Times}}{{cite news |last=Carson |first=Rob |date=October 5, 1992 |title=Congestion at the crater |page=A1 |work=The News Tribune}} The expected influx of tourists and their potential impact on the recovering habitat around the volcano alarmed scientists looking to preserve areas for sensitive research.{{cite news |date=October 11, 1992 |title=Scientists worried by new road at St. Helens |page=B1 |work=The Seattle Times |agency=Associated Press}} After finding that elk herds were leaving areas with improved highway access, the Forest Service established restricted zones within the national monument that prohibited off-trail hiking, pets, fires, and camping.{{cite news |last=Durbin |first=Kathie |date=May 14, 2000 |title=Recovery: Recreation's demands |pages=[https://www.newspapers.com/article/the-columbian-recovery-recreations-dem/131068211/ 17]–[https://www.newspapers.com/article/the-columbian-recovery-recreations-dem/131068221/ 18] |work=The Columbian |url=https://www.newspapers.com/article/the-columbian-recovery-recreations-dem/131068221/ |via=Newspapers.com |accessdate=September 1, 2023}}

Two additional visitor centers, Weyerhaeuser's Forest Learning Center and the former Hoffstadt Bluffs Visitor Center, opened in 1995 at milepost 33 and 1996 at milepost 27, respectively.{{cite news |last=Jackson |first=Kristin |date=May 14, 1995 |title=A new look at the volcano |page=K4 |work=The Seattle Times}}{{cite news |last=Callahan |first=Loretta |date=May 17, 1996 |title=Visitors center to debut |page=A1 |work=The Columbian |url=https://www.newspapers.com/article/the-columbian-visitors-center-to-debut/131068254/ |via=Newspapers.com |accessdate=September 1, 2023}} In May 1997, SR 504 was extended {{convert|7.5|mi|km}} to its current terminus at the newly opened Johnston Ridge Observatory, named for volcanologist David A. Johnston.{{cite news |date=May 17, 1997 |title=New window on a sleeping giant: 17 years ago, St. Helens awoke |page=A1 |work=The News Tribune}}{{cite news |last=Cowan |first=Ron |date=June 22, 1997 |title=Mount St. Helens, 17 years later: Rising from the ash |page=D3 |work=Journal and Courier |location=Lafayette, Indiana |url=https://www.newspapers.com/clip/23487149/mount_st_helens_rising_from_the_ash/ |via=Newspapers.com |access-date=September 5, 2018}} Construction of the extension included underground blasting to compact soil and provide one of the highway's bridges with a stable foundation.{{cite news |last=Goldsmith |first=Steven |date=December 12, 1992 |title=Explosions to compact loose earth in St. Helens area |page=B2 |work=Seattle Post-Intelligencer}} It replaced an original plan to build a forest road that would be used by shuttle buses between Coldwater Ridge and the Johnston Ridge facility.{{cite news |date=January 14, 1989 |title=New road will give view of St. Helens' crater |page=A6 |work=The Seattle Times}}

A long-proposed extension of SR 504 to the eastern side of the Mount St. Helens area gained traction in the early 2000s, sparking outcry from scientists and environmentalists.{{cite news |last=Pryne |first=Eric |date=July 27, 1993 |title=Crossing the volcano |page=A1 |work=The Seattle Times}}{{cite news |last=Durbin |first=Kathie |date=December 29, 2000 |title=Mount St. Helens: Proposed road meets opposition |page=A1 |work=The Columbian |url=https://www.newspapers.com/article/the-columbian-mount-st-helens-proposed/131068061/ |via=Newspapers.com |accessdate=September 1, 2023}} The {{convert|7 to 17|mi|km|adj=mid}} route, connecting Coldwater Lake to the existing Forest Highway 99 near Windy Ridge and beyond to Forest Highway 25, was supported by officials from Cowlitz and Lewis counties as a tourist draw and a potential evacuation route.{{cite news |last=Lester |first=David |date=August 8, 2000 |title=Road would hook up to Highway 12 at Randle |page=A1 |work=Yakima Herald-Republic |url=https://www.highbeam.com/doc/1P2-18457944.html |archive-url=https://web.archive.org/web/20181119095756/https://www.highbeam.com/doc/1P2-18457944.html |url-status=dead |archive-date=November 19, 2018 |via=HighBeam |url-access=subscription |access-date=September 11, 2018}}{{cite news |last=Middlewood |first=Erin |date=January 19, 2001 |title=Mt. St. Helens highway plans narrowed |page=D2 |work=The Oregonian}} WSDOT studied several options for the proposed highway, which enjoyed mixed public support, and estimated a cost of $18.5 million to construct one option and $44 million for another (equivalent to ${{Format price|{{Inflation|US-GDP|18500000|2001}}}} and ${{Format price|{{Inflation|US-GDP|44000000|2001}}}}, respectively, in {{Inflation-year|US-GDP}} dollars).{{inflation-fn|US-GDP}}{{cite news |last=Welch |first=Craig |date=May 18, 2001 |title=Towns isolated by volcano push new road for tourism |page=B1 |work=The Seattle Times}}{{cite news |last=Apalategui |first=Eric |date=April 4, 2001 |title=Public likes idea to extend SR 504 |work=The Daily News |location=Longview, Washington |url=https://tdn.com/public-likes-idea-to-extend-sr/article_80db94a6-83bc-543b-9ecd-272881b62c5f.html |access-date=September 11, 2018}} The proposed highway was rejected by state legislators due to its cost, despite attempts at salvaging the cheaper proposal by converting it into a toll road.{{cite news |last=Apalategui |first=Eric |date=April 8, 2002 |title=SR 504 fate may be in voters' hands |work=The Daily News |location=Longview, Washington |url=https://tdn.com/sr-fate-may-be-in-voters-hands/article_7393a5d4-50f5-5a05-8395-81b447c68bd9.html |access-date=September 11, 2018}}{{cite news |last=Apalategui |first=Eric |date=April 1, 2004 |title=Locke pulls plug on volcano road |work=The Daily News |location=Longview, Washington |url=https://tdn.com/business/local/locke-pulls-plug-on-volcano-road/article_14c9cb7a-e9fd-5446-923f-1f7d9e6f71b0.html |access-date=September 11, 2018}}{{cite news |last=Durbin |first=Kathie |date=October 18, 2004 |title=Push for St. Helens road link smolders on |page=C1 |work=The Columbian |url=https://www.newspapers.com/article/the-columbian-push-for-st-helens-road-l/131068113/ |via=Newspapers.com |accessdate=September 1, 2023}}

From 2004 until 2006, increased volcanic activity at Mount St. Helens caused a surge in tourist traffic on SR 504, along with periodic shutdowns of the Johnston Ridge section.{{cite news |last=Schwarzen |first=Cristopher |date=October 2, 2004 |title=Eruption means flow of dollars into area from more visitors |page=A12 |work=The Seattle Times}}{{cite news |last=Bernton |first=Hal |date=October 4, 2004 |title=Mount St. Helens poised to erupt; Scientists wait and watch |page=A1 |url=http://old.seattletimes.com/html/localnews/2002053363_volcano04m.html |work=The Seattle Times |access-date=September 4, 2018}} An evacuation of the area was ordered in early October 2004 due to seismic activity, indicating a possible buildup of magma, forcing 2,500 visitors to leave the Coldwater and Johnston centers for several days.{{cite news |last=Brettman |first=Allan |date=October 3, 2004 |title=St. Helens shows dire signs; worst is yet to come |page=A1 |work=The Oregonian}} The evacuation was later cancelled and other restrictions were relaxed after steam eruptions diffused pressure inside the volcano.{{cite news |last=Florip |first=Eric |date=September 25, 2014 |title=Mount St. Helens came back to life a decade ago |url=https://www.columbian.com/news/2014/sep/25/mount-st-helens-volcano-2004-eruption/ |work=The Columbian |access-date=September 6, 2018}} A minor mudslide in March 2007 blocked a section of SR 504 near Kid Valley and was removed after a week-long cleanup by WSDOT crews.{{cite news |date=March 29, 2007 |title=SR 504 to remain closed through weekend |work=The Daily News |location=Longview, Washington |url=https://tdn.com/news/sr-to-remain-closed-through-weekend/article_1a2414dc-6ad8-5f99-bda4-66dccbd0a0ea.html |access-date=September 11, 2018}}{{cite press release |date=April 2, 2007 |title=Major Debris Clean-Up Complete, SR 504 East of Kid Valley Opens to Traffic |url=http://wsdot.wa.gov/News/2007/04/02_SR504Debris.htm |publisher=Washington State Department of Transportation |url-status=dead |archive-url=https://web.archive.org/web/20091223141239/http://wsdot.wa.gov/News/2007/04/02_SR504Debris.htm |archive-date=December 23, 2009 |access-date=September 11, 2018}}

A mudslide and debris flow, known as the 2023 South Coldwater Slide, occurred on May 14, 2023, destroying the {{convert|85|ft|m|adj=mid}} Spirit Lake Outlet Bridge and severing SR 504 northeast of Johnston Ridge Observatory at milepost 49. Twelve people were airlifted from the area beyond the mudslide; the observatory's seasonal reopening was postponed and the highway east of Coldwater Lake was closed to all traffic.{{cite news |last=Kauffman |first=Brennen |date=May 15, 2023 |title=Debris slide blocks SR 504 near Coldwater Lake; a dozen people rescued |url=https://tdn.com/news/local/update-debris-slide-blocks-sr-504-near-coldwater-lake-a-dozen-people-rescued/article_aa7f8ece-f336-11ed-9721-33875703a3fa.html |work=The Daily News |location=Longview, Washington |accessdate=May 16, 2023}}{{cite press release |last=Greenwell |first=Tamara |date=May 16, 2023 |title=Upper SR 504/Spirit Lake Memorial Highway closed until further notice |url=https://wsdot.wa.gov/about/news/2023/upper-sr-504-spirit-lake-memorial-highway-closed-until-further-notice |publisher=Washington State Department of Transportation |accessdate=May 16, 2023}} WSDOT contractors cleared debris over the highway by July and created a temporary gravel road to access Johnston Ridge for vehicle retrieval and to prepare for reopening in 2024,{{cite news |date=July 15, 2023 |title=Mount St. Helens mudslide cleared enough for drivers to retrieve stranded vehicles |url=https://www.oregonlive.com/pacific-northwest-news/2023/07/mount-st-helens-mudslide-cleared-enough-for-drivers-to-retrieve-stranded-vehicles.html |work=The Oregonian |accessdate=September 1, 2023}}{{cite news |last=Brown |first=Sydney |date=July 17, 2023 |title=Motorists retrieve vehicles stranded by landslide on highway to Mount St. Helens |url=https://www.columbian.com/news/2023/jul/17/motorists-retrieve-vehicles-stranded-by-landslide-on-highway-to-mount-st-helens/ |work=The Columbian |accessdate=September 1, 2023}} but the interim roadway was washed out in November due to a collapsed culvert caused by heavy rainfall and erosion unrelated to the earlier landslide.{{cite news |last=Vander Stoep |first=Isabel |date=November 16, 2023 |title=Temporary 'fix' after landslide on Spirit Lake Highway has failed, WSDOT says |url=https://www.chronline.com/stories/temporary-fix-after-landslide-on-spirit-lake-highway-has-failed-wsdot-says,329432 |work=The Chronicle |accessdate=December 7, 2023}} WSDOT announced in early 2024 that because of the costs and difficulties in making repairs to the bypass, based on a limited construction window due to weather and elevation as well as the steepness of the terrain, the highway and access to the observatory was to remain closed until 2026.{{cite news |author1=KGW staff |title=Mount St. Helens' Johnston Ridge Observatory closed until 2026 after landslide on Spirit Lake Highway |url=https://www.kgw.com/article/news/regional/southwest-washington/mount-st-helens-landslide-johnston-ridge-observatory-closed-2026/283-d29c8ef0-dc42-453b-a5c2-69fef06160f9 |access-date=February 7, 2024 |work=KGW 8 News (Portland, Oregon) |date=February 6, 2024}} The closure timeline was revised by WSDOT to April 2027, with construction to rebuild the route not slated until April 2026.{{cite news |last1=Spykerman |first1=Monica |title=Johnston Ridge Observatory and Spirit Lake Highway are slated to reopen in spring of 2027 |url=https://www.columbian.com/news/2024/aug/07/johnston-ridge-observatory-and-spirit-lake-highway-are-slated-to-reopen-in-spring-of-2027/ |access-date=August 13, 2024 |work=The Columbian |date=August 7, 2024}}

{{WAinttop|length_ref=}}

{{WAint

|county=Cowlitz

|cspan=4

|location=Castle Rock

|mile=0.00

|road={{jct|state=WA|I|5|SR|411|BL|5|dab3=Castle Rock|dir2=south|dir3=south|name3=Huntington Avenue|location1=Portland|city2=Seattle|city3=Castle Rock}}

|notes=Western terminus

}}

{{WAint

|location=none

|mile=14.69

|road={{jct|state=WA|SR|505|dir1=west|to2=to|I|5|city1=Toledo}}

|notes=

}}

{{Jctint

|location=none

|mile=21.03

|road={{jct|state=WA|SR-Spur|504|name1=Sediment Dam Road}}

|notes=Former alignment of SR 504

}}

{{Jctplace

|location_special=Mount St. Helens NVM

|lspan=2

|mile=44.32

|place=Mount St. Helens National Volcanic Monument boundary

}}

{{WAint

|county=Skamania

|mile=51.76

|road=Johnston Ridge Observatory

|notes=Eastern terminus

}}

{{jctbtm}}

{{infobox road small

|state=WA

|type=WA-Spur

|route=504

|length_mi=0.87

|length_ref=

|location=Cowlitz County

|formed=1991

}}

SR 504 has a short spur route east of Kid Valley that runs along Sediment Dam Road. It follows a {{convert|0.87|mi|km|adj=mid}} section of the former highway and terminates near the Toutle River Sediment Dam at a viewpoint and WSDOT maintenance facility {{cite web |date=June 2018 |title=Vehicle Operator's Handbook and Fuel Station Locations |page=99 |url=https://www.wsdot.wa.gov/publications/manuals/fulltext/M53-55/FuelStations.pdf |publisher=Washington State Department of Transportation |access-date=September 5, 2018}} An average of 50 vehicles use the road on a daily basis, according to annual daily traffic data measured by WSDOT in 2016.

{{clear}}

{{reflist}}

{{attached KML|display=title,inline}}

• {{Commons category-inline}}
• [https://www.angelfire.com/wa2/hwysofwastate/sr504.html Highways of Washington State]

{{State highways in Washington related to I-5}}

Category:Gifford Pinchot National Forest

Category:Mount St. Helens

504

Category:Transportation in Cowlitz County, Washington

Category:Transportation in Skamania County, Washington