I-90

About I-90

Also known as Jane Addams Memorial Tollway, Northwest Tollway, Massachusetts Turnpike.

From Seattle, WA (SR 519) to Boston, MA (Route 1A)

Interstate 90 is the longest Interstate Highway in the United States, running roughly 3,020 miles from Seattle, Washington, to Boston, Massachusetts, across thirteen states. From the Pacific Northwest it climbs the Cascade Range, crosses the dry interior of Washington and the panhandle of Idaho, then traverses the mountains and high plains of Montana and Wyoming. It continues across South Dakota, Minnesota, and Wisconsin into the Great Lakes region, passing through Chicago, Cleveland, and Buffalo before reaching the Atlantic at Boston.

The western mountain sections include some of the most dramatic terrain on the Interstate system. The route crosses Snoqualmie Pass in the Washington Cascades and climbs through the Rocky Mountains in Montana, where Homestake Pass marks the highest point on the entire Interstate network. Near Seattle the highway uses floating bridges across Lake Washington and the Mount Baker Ridge Tunnel to enter the city.

Across the eastern half the highway runs through the agricultural Midwest and the industrial Great Lakes states, linking Sioux Falls, Madison, Chicago, Cleveland, Buffalo, Syracuse, and Albany. Many of these segments are tolled, including the Indiana Toll Road, the Ohio Turnpike, the New York State Thruway, and the Massachusetts Turnpike, along with the Chicago Skyway. In Boston it ends near the harbor after passing through the Ted Williams Tunnel.

Interstate 90 carries heavy long-haul freight and serves as a primary coast-to-coast corridor across the northern tier of the country. It connects a long string of major interior cities and forms one of the main links between the Pacific Northwest and the Northeast.

State-by-state mileage

State	Miles
Washington	297.5
Idaho	73.5
Montana	551.7
Wyoming	208.8
South Dakota	412.5
Minnesota	275.7
Wisconsin	187.1
Illinois	123.9
Indiana	156.3
Ohio	244.8
Pennsylvania	46.3
New York	490.8
Massachusetts	135.7
Total	3,204.6

History

Interstate 90 was among the routes designated in 1957 under the federal Interstate program established the year before, and it was built in many segments over the following decades. The mountain crossings in the Cascades and the Rockies, together with the floating bridges across Lake Washington, were among the more demanding engineering tasks along the route.

Numerous older toll roads in the eastern states were incorporated into the corridor, and the assembly of these segments with new construction produced a continuous freeway spanning the northern United States from coast to coast.

Major cities and places

Notable features

• Snoqualmie Pass
• Homestake Pass
• Lake Washington floating bridges
• Mount Baker Ridge Tunnel
• Ted Williams Tunnel
• Chicago Skyway

Did you know

• It is the longest Interstate Highway in the United States.
• It passes through thirteen states between Seattle and Boston.
• Homestake Pass in Montana is the highest point on the entire Interstate Highway system.
• Many eastern segments are toll roads, including the Indiana Toll Road, the Ohio Turnpike, the New York State Thruway, and the Massachusetts Turnpike.
• It uses floating bridges to cross Lake Washington near Seattle.