Interstate 90: route guide

I-90 is the northern tier of the US interstate system: it starts in Seattle south of downtown, crosses the Cascade Range, the Rocky Mountains, the Great Plains and the Midwest, then follows a chain of toll turnpikes from Illinois to Boston. It is the longest transcontinental interstate in the country.

The route is paired with I-80 on the Indiana Toll Road and the Ohio Turnpike between Chicago and Cleveland, and with I-94 between Tomah and Madison, Wisconsin, and again in Chicago. I-94 splits off at Billings, Montana as a northern branch and rejoins the corridor several times before ending at the Canadian border at Port Huron, Michigan.

West of Illinois the highway is toll-free. From South Beloit, Illinois eastward it runs as a series of turnpikes: the Jane Addams Memorial Tollway, Chicago Skyway, Indiana Toll Road, Ohio Turnpike, New York State Thruway and Massachusetts Turnpike. The Pennsylvania section is the exception and stays toll-free.

The table below splits the route into drivable stages. Distances and times are approximate and assume no long detours; add time for mountain weather, Chicago traffic and turnpike service areas.

Seattle to Spokane crosses Snoqualmie Pass in the Cascades; the stretch from Seattle to Ellensburg is the Mountains to Sound Greenway, the first interstate designated a National Scenic Byway. Spokane to Billings runs through the Idaho panhandle and western Montana, past Coeur d'Alene and Missoula. Billings to Sioux Falls is the long, empty Plains leg through Sheridan, Gillette and the Black Hills turnoff near Rapid City.

Sioux Falls to Chicago passes Albert Lea, La Crosse, Tomah and Madison, then Rockford and Elgin into the city. Chicago to Cleveland uses the Indiana Toll Road and Ohio Turnpike, with Sandusky on Lake Erie as the natural break. Cleveland to Albany crosses Erie, Buffalo, Rochester and Syracuse on the New York State Thruway. Albany to Boston is the last leg, through the Berkshires and Worcester to Logan Airport.

May to October is the practical window. Snoqualmie Pass and the Montana mountain sections can see snow and closures from November into April, and the Plains states get high winds and ice. Summer brings long daylight and open services but also peak prices and crowds around Yellowstone, the Black Hills and the Great Lakes.

Shoulder months — late May, September and early October — give you the same open roads with fewer people. If you only want the eastern half, the turnpike corridor from Chicago to Boston is drivable year-round, though lake-effect snow around Erie, Buffalo and Syracuse is a real winter hazard.

Plan around holiday weekends: Memorial Day, July 4 and Labor Day fill motels along the whole route.

Motels and chain hotels cluster at every interstate exit, so you rarely need to book far ahead outside holiday weekends and the Black Hills and Yellowstone gateway towns in summer. Booking.com, Agoda and Hostelworld cover the bigger cities; small-town motels are often cheaper by phone or walk-in.

Sensible overnight stops that break the driving evenly: Spokane or Coeur d'Alene, Missoula or Billings, Rapid City or Sioux Falls, Madison or Chicago, Sandusky or Cleveland, Buffalo or Syracuse, and Albany. Camping is available in the national forests of Washington, Idaho and Montana and in the Black Hills.

This is a long drive across varied terrain and jurisdictions. Carry a valid licence for the vehicle class you are driving, and check the rules for any rental: most US rental companies allow one-way drop-offs between major cities for a fee, and some restrict cross-country returns.

Keep a paper or offline map for the mountain and Plains sections where phone signal drops. Winter tyres or chains may be required on mountain passes in cold months; check state transport department road conditions before each mountain leg. Tolls on the eastern turnpikes are usually paid by transponder or plate billing, so confirm how your rental handles them.

Fuel and food are plentiful on the interstates but sparse on some Plains stretches; fill up when you can. Carry water, a spare tyre and basic tools.