Interstate 90 (I-90) - Connecting Washington East-West

The Interstate 90 (I-90) is the longest interstate highway in the United States, crossing from East-to-West from Boston, Massachusetts to Seattle, Washington. It connects the two largest cities in the state, Spokane and Seattle.

I-90 is almost 3,100 miles long. In Seattle, the highway ends next to Safeco Field and Qwest field, the two major sports stadiums in the city hosting the Seattle Mariners baseball and the Seattle Seahawks football. It is the only major interstate connecting eastern and western Washington although there are two state routes that do so.

The average annual daily traffic on the I-90 in the Seattle area is over 160,000 vehicles per day.

In Seattle, the I-90 crosses Lake Washington incorporating two of the longest floating bridges in the world from Seattle to Mercer Island.  

Approximately 40 miles east of Bellevue, the I-90 crosses the Cascade Mountains at Snoqualmie Pass at an elevation of over 3,022 feet.  Approximately 10 million travelers cross Snoqualmie Pass each year. The Snoqualmie Pass can be treacherous during the winter time as an average snowfall of 33 feet of snow falls on the highway. Maintenance crews work 24 hours a day, seven days a week to treat the roadway . At times, however, the roadway has to be closed for avalanche control work . The highway can also be closed due to serious car accidents. In 2007, the I-90 was closed for nearly 200 hours due to avalanche and collisions.

137 miles east of Seattle, I-90 crosses the Columbia River at Vantage and enters Spokane at mile post 279.

The I-90 provides exits to the following cities: Bellevue, Cle Elum, Ellensburg, Issaquah, Liberty Lake, Mercer Island, Moses Lake, North Bend, Seattle, Spokane, Spokane Valley, Sprague and crosses six counties: Adams, Grant, King, Kittitas, Lincoln, and Spokane.

We advise checking the Washington State Department of Transportation webcams before crossing the Snoqualmie Pass in the winter. Click here to access all of the webcams on the I-90.

Map Interstate 90 (I-90) - Connecting Washington East-West