Updated at: 12-06-2022 - By: Lucas

Interstate 90 (I-90) is the longest interstate in the United States. It goes from Boston in the east to Seattle in the west, and it starts in the east in Boston.

The eastern end of I-90 is less than half a mile from Boston Harbor, and the western end is about the same distance from Elliott Bay. This means that both the Atlantic and Pacific Oceans are less than a mile away from I-90.

It really is a highway from coast to coast.

How long is Interstate 90?

The whole length of Interstate 90 is 3,021 miles (or 4,862 km).

What states does Interstate 90 go through?

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I-90 goes through 13 different states.

These are the states:


New York City







The state of South Dakota





How long is I-90 in MA?

138 miles

How long is I-90 in NY?

386 miles

How long is I-90 in PA?

46 miles

How long is I-90 in OH?

243 miles

How long is I-90 in IN?

156 miles

How long is I-90 in IL?

108 miles

How long is I-90 in WI?

187 miles

How long is I-90 in MN?

276 miles

How long is I-90 in SD?

413 miles

How long is I-90 in WY?

210 miles

How long is I-90 in MT?

554 miles

How long is I-90 in ID?

74 miles

How long is I-90 in WA?

298 miles

Which cities does Interstate 90 go through?

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Along with Seattle and Boston, where it starts and ends, Interstate 90 goes through or near a number of large cities. For the purposes of this article, we’ll call a city “large” if it has 100,000 or more people living there.

These are their names:

Springfield, MA

Syracuse, New York

Rochester, NY

Buffalo, NY

OH, Cleveland

Toledo, OH

South Bend, Indiana

Chicago, Illinois

Rockford, Illinois

Madison, Wisconsin

Rochester, MN

Sioux Falls, SD

Billings, MT

Spokane, WA

I-90 also goes through a number of smaller cities, such as:

Framingham, MA

MA, Worcester

Albany, NY

Utica, NY

Erie, PA

Gary, Indiana

Rapid City, South Dakota

Bozeman, MT

Missoula, MT

Coeur d’Alene, ID

Other Notable Places Along Interstate 90

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Along with the cities it goes through, I-90 goes by a number of interesting towns or attractions.

These things are:

State Forest of October Mountain (Appalachian Trail Head)

Lake Erie (rolls right over it in Cleveland)

The University of Notre Dame

National Park of Badlands

National Forest of the Black Hills

Sturgis, SD (known for its motorcycle rally)

Bighorn Forest National Park

The National Forest of Mt. Baker-Snoqualmie

How long did it take to build I-90?

It took 31 years to build most of Interstate 90. It was first ordered in 1956, and by 1987, it had gone all the way across the country.

But in 1993, it went farther to Seattle, and in 2003, it went farther to Boston.

So, I-90 was built between 1956 and 2003, which means it took 47 years to finish!

How long does it take to drive I-90?

When speed limits are taken into account, it takes about 45 hours to drive from one end of I-90 to the other, or almost two days if you drive straight through. (Let’s assume you have a very nice car and a second driver.)

But that doesn’t take into account traffic, gas stops, or any other stops you’ll want to make along the way (there will be a lot).

So, if you only drive for eight hours a day, which is much more reasonable, you’ll have nearly six days of good road trip time along the U.S.’s northernmost cross-country interstate.

See What Is The Longest Highway In The U.S.? for information about the longest highway in the country.