Snoqualmie Pass

Snoqualmie Pass carries I-90 over the Cascades at 3,022 feet, near milepost 52 and about 50 miles east of downtown Seattle. From November 1 to April 1, any vehicle over 10,000 pounds GVWR must carry chains between North Bend (MP 32) and Ellensburg (MP 101), whatever the weather.

WSDOT counts an average of 34,000 vehicles a day over the pass, thousands of them trucks. I-90 is the only interstate across the Washington Cascades: I-5 stays west of the range and I-82 stays east of it. When Snoqualmie closes, the year-round alternatives are US 2 over Stevens Pass, which sits about 1,000 feet higher at 4,061 feet, and US 12 over White Pass. WSDOT shuts SR 410 over Chinook Pass and SR 20, the North Cascades Highway, for the winter. Both US 2 and US 12 are on the same November to April chain-carry list as I-90.

East of the summit, the road runs along Keechelus Lake between Hyak (MP 55) and Keechelus Dam (MP 60.5). Since 2009 WSDOT has been rebuilding the 15 miles from Hyak to Easton as a six-lane freeway under the I-90 Snoqualmie Pass East project. The finished phases, Hyak to the Stampede Pass interchange, put the highway on twin avalanche bridges near MP 58 and added a wildlife overcrossing at MP 61.3. Phase 3, Cabin Creek to West Easton, is under construction with completion scheduled for fall 2028. In 2026 eastbound traffic runs on the westbound side between MP 68 and 70, with two lanes open each way. Phases 3 and 4 add truck-climbing lanes and new chain-up areas. Phase 4, Stampede Pass to Cabin Creek, has not started.

• Summit elevation 3,022 ft (WSDOT), at I-90 milepost 52
• Vehicles over 10,000 lb GVWR must carry chains Nov 1 to Apr 1 from North Bend (MP 32) to Ellensburg (MP 101), plus at least two extra chains (WAC 204-24-050)
• Heavy vehicles have to mount chains once WSDOT posts "Traction tires required" (WSDOT)
• Ignoring a posted chain requirement is a $500 traffic infraction, assessments included (RCW 47.36.250)
• Avalanche control delays usually run 30 minutes to two hours, longer in severe storms (WSDOT)
• The weather station at the pass averaged about 420 inches of snow a year over its 1910 to 2002 record (Western Regional Climate Center)

WSDOT sets the traction requirement for each direction on its mountain pass report and posts it on signs at the controlled section. The Washington State Patrol enforces it. There are four levels. "Traction tires advised" bans oversize loads. "Traction tires required" means passenger vehicles need approved traction tires and every vehicle over 10,000 pounds GVWR has to put chains on. At "Tire chains required," all vehicles chain up except four-wheel and all-wheel drive, which still have to carry chains. "Chains required on all vehicles" takes away that exception.

For a heavy truck, the second level is the one that matters. Traction tires and studded tires do not count as chains. For the common five-axle rig, a tractor with tandem drives pulling a tandem-axle trailer, WAC 204-24-050 calls for chains on at least four drive tires: every tire on one drive axle, or one tire on each side of both drive axles. One tire on either of the trailer's last two axles must be chained too. Chains must have two side chains and enough hardened metal cross chains that one is always on the road. Plastic chains are not allowed. Cable chains and some alternative traction devices count if the State Patrol has approved them for your axle configuration, so check the WSP list before you buy.

The carry rule applies even on a dry November day. From November 1 to April 1, vehicles over 10,000 pounds GVWR must carry enough chains for their configuration on I-90 between MP 32 and MP 101, and on I-82 between Ellensburg (Exit 3) and Selah (Exit 26). They must also carry at least two extra chains in case conditions get worse or a chain breaks. Local deliveries shown on the bill of lading are exempt if the truck stays outside the chain area and does not cross the pass. Failing to obey a posted requirement is a traffic infraction with a $500 penalty including all statutory assessments (RCW 47.36.250).

Oversize permit moves are prohibited on the pass while any traction advisory is posted. If you would rather not chain up yourself, WSDOT permits private chain installers who work at signed spots on I-90 when chains are required. As of September 2026, WSDOT lists their rate for vehicles over 10,000 pounds at $25 per tire chained and $5 per tire to take off. They are not required to show up, so carry chains you can install yourself.

WSDOT publishes the full pass report from November 1 to April 1. Outside that window it updates the page only when conditions cause delays of an hour or more.

Native American foot trails crossed the Cascades at Snoqualmie long before settlers arrived, and tribes including the Snoqualmie and Yakama used the route for trade because it was the lowest pass in the region (WSDOT). A wagon road between Seattle and Ellensburg was finished in 1867. On July 1, 1915, Governor Ernest Lister dedicated the Sunset Highway over the pass as the state's first passable route through the Cascades (HistoryLink). The state highway department first kept the road open through an entire winter in 1931. The road later became US 10, was widened to four lanes in the 1950s and 1960s, and became I-90.

In 1950 the state built the Lake Keechelus snowshed to keep slides off the road east of the summit. The 500-foot shed came down in April 2014, replaced by twin avalanche bridges about 1,200 feet long that let slides run underneath. On the west side, WSDOT avalanche crews used artillery from the 1980s onward: a 105mm recoilless rifle, an M60 tank and a 105mm howitzer. Setting up the guns could close I-90 for up to six hours before the first shot. In 2025 WSDOT put up the first solar-powered Remote Avalanche Control tower on Snoqualmie, just west of the pass. Crews fire it from miles away, and WSDOT has ended artillery use on the pass.