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Snoqualmie Pass

Coordinates: 47°25′23″N 121°24′40″W / 47.423°N 121.411°W / 47.423; -121.411
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Snoqualmie Pass
I-90 through Snoqualmie Pass
Elevation3,015 ft (919 m)[1]
Traversed by I-90[2]
LocationKing / Kittitas counties, Washington, U.S.[1]
RangeCascade Range
Coordinates47°25′23″N 121°24′40″W / 47.423°N 121.411°W / 47.423; -121.411[1]
Snoqualmie Pass is located in Washington (state)
Snoqualmie Pass
Snoqualmie Pass
Snoqualmie Pass is located in the United States
Snoqualmie Pass
Snoqualmie Pass

Snoqualmie Pass is a mountain pass that carries Interstate 90 (I-90) through the Cascade Range in the U.S. state of Washington. The pass summit is at an elevation of 3,015 feet (919 m), on the county line between Kittitas County and King County.[1]

Snoqualmie Pass has the lowest elevation of the three east–west mountain routes across Washington State that are kept open year-round, along with Stevens Pass (US 2) to the north, and White Pass (US 12) to the south. I-90 is the primary commercial artery between Seattle and points east, carrying an average of 29,000 vehicles through the pass per day.[3] I-90 is the only divided highway crossing east–west through the state.[a]

The pass lends its name to a census-designated place (CDP) located at the summit (Snoqualmie Pass, Washington). Both the CDP and Snoqualmie Pass are named after the Snoqualmie people of the valley to the west.


Snoqualmie Pass's feet (below ~1-2000 ft elevation)[5] have a Csb (warm-summer mediterranean) climate, but as it climbs into the Cascades, it passes through a microclimate (warm-summer mediterranean continental, Dsb) characterized by considerable precipitation, especially during winter, and at times hazardous conditions for travelers. The average annual precipitation is over 100 inches; snowfall averages over 400 inches. The average annual number of days with measurable precipitation is over 170. Frosts can occur at any time of year, and snow can fall any time outside midsummer.

The summit of Snoqualmie Pass is in hardiness zone 7b, with a yearly mean minimum of 9 °F (−13 °C).[6]

Climate data for Snoqualmie Pass
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Record high °F (°C) 56
Mean daily maximum °F (°C) 32.4
Mean daily minimum °F (°C) 20.9
Record low °F (°C) −17
Average precipitation inches (mm) 15.69
Average snowfall inches (cm) 104.4
Source: [7]

The rapidly changing conditions require special cautions, relayed to motorists via variable message displays along I-90.[8] Depending on traction they may call for tire chains to be installed, usually on large trucks but occasionally on smaller vehicles as well. Chain-up areas are provided along the side of the Interstate to facilitate the placement of chains. The pass has been subjected to closures when weather conditions become extreme.[9]

A snow shed, constructed in 1950 when the road was known as US 10, formerly covered the westbound lanes, but it has been replaced by avalanche bridges that stand away from the slope to allow slides to pass under the road, as of April 2014.[10] WSDOT maintains cameras at selected locations along the pass to monitor weather conditions. Some of these cameras can be viewed via the internet.[11]


Ben Evans, Director of Playfields of the Seattle Parks Department, skiing at Snoqualmie Pass, 1935. For five years in the 1930s, the department operated a ski park at the Pass, about 54 miles (87 km) from the city.

The area around Snoqualmie Pass consists of mountain chalets that are mainly seasonally occupied by residents of the Seattle metropolitan area, with approximately 150 year-round residents. Winter sports are the main draw, but outdoor recreation is available year-round.

The Pacific Crest Trail crosses through Snoqualmie Pass and a variety of other trails are also available for hiking and climbing in the summer, cross-country skiing and snowshoeing during the winter months.

Snoqualmie Pass is also the site of the Summit at Snoqualmie, a group of alpine ski areas managed by Boyne USA Resorts. The Summit consists of four ski areas: Alpental, Summit West (formerly named Snoqualmie Summit), Summit Central (formerly Ski Acres), and Summit East (formerly Hyak).[12] The Summit at Snoqualmie is the closest ski area to Seattle.

Snowmobiling just east of the pass is also popular during the winter months. Also in the summer and fall, paragliders and hang gliders may be seen flying above the valley, along the ridge and landing at Lake Keechelus.


Variable speed limit sign along I-90
Snowshed constructed 1950, removed in 2014.[13]

Snoqualmie Pass was well known to the Native Americans of the region. Hudson's Bay Company trappers and traders were active in the Snoqualmie and Yakima valleys during the early 19th century. They knew about Snoqualmie Pass but information about their use of it is vague. A possible early use of the pass was that of A.C. Anderson, who drove cattle across the Cascades in 1841, via a pass he called "Sinahomish Pass".[14]

Captain George B. McClellan and his lieutenant Abiel W. Tinkham explored the Snoqualmie Pass region in 1853 and 1854. Their goal was to find a pass better suited for a railroad than Naches Pass, where the Naches Trail crossed the Cascade Mountains. They explored from the east side of the mountains, reaching the vicinity of Yakima Pass (47°20′11″N 121°25′57″W / 47.3365°N 121.4324°W / 47.3365; -121.4324). Tinkham continued down the west side via the Cedar River. McClellan decided not to examine Snoqualmie Pass itself because of unfavorable reports from Natives.[14]

In 1856, Major J.H.H. Van Bokkelen, then of the Washington Territory Volunteers (militia), crossed Snoqualmie Pass on a scouting mission. In 1858 several large pack trains bound for mines east of the Cascades crossed the pass. In 1865 a number of Seattle citizens, including Arthur A. Denny, explored the Cedar River, Snoqualmie Pass, and Naches Pass. They reported that Snoqualmie Pass route was a better choice for a road than the old Indian trail over Yakima Pass. By 1867 a toll road had been built over Snoqualmie Pass. Intended to be suitable for wagons, for years the road was only usable by pack trains and for cattle drives.[14]

The Chicago, Milwaukee, St. Paul and Pacific Railroad (the "Milwaukee Road") completed a line through Snoqualmie Pass in 1909, part of its Pacific Extension. This grade was soon replaced in 1914 by the 2¼-mile (3.6 km) Snoqualmie Tunnel, from Hyak due west to Rockdale, at an approximate elevation of 2,600 feet (790 m), more than 400 feet (120 m) below the pass. The rail line was abandoned 44 years ago in 1980, and the tunnel is presently a multi-use trail for bicyclists and hikers, part of Iron Horse State Park.[15] During tunnel construction, an improved wagon road was built over the pass. Near the original rail line, the Sunset Highway was opened through the pass in 1915.[16]

In 1927, the road over the pass became U.S. Route 10; it began to be plowed and kept open during winter in 1931.[17] By 1933, the first alpine ski hill was cleared at Snoqualmie Pass, and U.S. 10 was finally paved in 1934.

In 1946, tunnel engineer Ole Singstad proposed the construction a tunnel under Snoqualmie Pass to avoid the most treacherous section of the route.[18] On June 24, 1946, seven players on the Spokane Indians minor league baseball team, and their manager, were killed when their bus veered through a guard rail on the Snoqualmie Pass Highway and plunged down a 500-foot embankment and into a ravine.[19]

In 1969, construction of U.S. 10's replacement, Interstate 90, began across the pass.[20][21][22]

Since 1991, the Mountains to Sound Greenway Trust has acted to protect the scenic value of the I-90 corridor over Snoqualmie Pass.[23]

Snoqualmie Pass landmarks

See also[edit]


  1. ^ Interstate 84 is on the Oregon side of the Columbia Gorge, and carries traffic diverted during pass closures.[4]


  1. ^ a b c d "Snoqualmie Pass". Geographic Names Information System. United States Geological Survey, United States Department of the Interior. Retrieved August 31, 2015.
  2. ^ Google (August 31, 2015). "Snoqualmie Pass" (Map). Google Maps. Google. Retrieved August 31, 2015.
  3. ^ "Annual Traffic Report". Washington State Department of Transportation. Retrieved August 31, 2015.
  4. ^ Eustice, J. Bradley; Sage, Jeremy (May 2, 2016). Reroute or Wait It Out: Estimating Optimal Route Decisions in the Presence of Unexpected Delays. Freight Policy Transportation Institute, Washington State University.
  5. ^ "Life Zones in Washington".
  6. ^ "Simulated historical climate & weather data for Snoqualmie Pass". meteoblue. Retrieved March 1, 2024.
  7. ^ "Snoqualmie Pass, Washington (457781)". Western Regional Climate Center. Retrieved July 11, 2016.
  8. ^ Smarter Highways 102: Variable Speed Limits
  9. ^ Snoqualmie Pass reopens after hours of closure - KOMO News
  10. ^ "WSDOT - I-90 - Snoqualmie Pass East - Hyak to Keechelus Dam (Phase 1) - I-90 Snowshed Removal". Archived from the original on April 30, 2014. Retrieved April 22, 2014.
  11. ^ WSDOT - Snoqualmie Pass Road and Weather Conditions
  12. ^ Summit at Snoqualmie
  13. ^ Archived at Ghostarchive and the Wayback Machine: "I-90 Snowshed Removal Time Lapse". YouTube.
  14. ^ a b c Beckey, Fred (2000). Cascade Alpine Guide: Climbing and High Routes: Columbia River to Stevens Pass (3rd ed.). The Mountaineers. p. 149. ISBN 978-0-89886-577-6.
  15. ^ Mapes, Lynda V. (July 6, 2011). "Snoqualmie Tunnel gives cyclists, riders cool new link". Seattle Times. Retrieved January 31, 2018.
  16. ^ Washington State Legislature (1913). "An act relating to public highways, classifying the same and naming and fixing the routes of certain state roads.". Session Laws of the State of Washington. Olympia, WA: State of Washington. 1913 chapter 65, p. 221.: "A highway starting from the Pacific Highway at Renton, Washington; thence over the most feasible route by the way of Snoqualmie Pass into the Yakima River Valley; thence by way of Wenatchee, over the most feasible route, through Waterville and Spokane, to the state boundary, which shall be known as the Sunset Highway."
  17. ^ Washington state department of transportation. (n.d.). Retrieved from http://www.wsdot.wa.gov/Projects/I90/SnoqualmiePassEast/History.htm
  18. ^ Robinson, Herb (August 21, 1970). "I-90 dispute revives talk of Cascade tunnel". The Seattle Times. p. A13.
  19. ^ "8 SPOKANE BASEBALL PLAYERS DEAD IN CRASH OF THEIR BUS", Spokane Daily Chronicle, June 25, 1946, p1
  20. ^ Bureau of Public Roads & American Association of State Highway Officials (November 11, 1926). United States System of Highways Adopted for Uniform Marking by the American Association of State Highway Officials (Map). 1:7,000,000. Washington, DC: United States Geological Survey. OCLC 32889555. Retrieved November 7, 2013 – via Wikimedia Commons.
  21. ^ Department of Highways, Highway Map: State of Washington, Revised to April 1, 1933
  22. ^ Department of Highways, Highways of the State of Washington (Rand McNally), 1939
  23. ^ About Us - Mountains to Sound Greenway Accessed August 31, 2015

Further reading[edit]

  • Prater, Yvonne (1995) [1981]. Snoqualmie Pass: From Indian Trail to Interstate. The Mountaineers. ISBN 0898860156.

External links[edit]