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What Is The Longest Highway In The U.S.?

The longest highway in the United States is U.S. Route 20 (US 20), which, like the country’s longest interstate, crosses the upper portion of the country.

Also like the longest interstate in the U.S. (I-90), Route 20 begins in Boston and actually follows the path of I-90 through the east, winding and curving around and running roughly parallel to I-90 all the way to Rockford, Illinois.

From there, US 20 splits from I-90 (though the two remain relatively parallel), with I-90 crossing higher across the plains and west to Seattle, while Route 20 runs between 75 and 200 miles south of I-90 (north of I-80) before terminating in Newport, Oregon.

How long is U.S. Route 20?

Route 20 has a total distance of 3,365 miles (or 5,415 km).

What states does Route 20 go through?

Route 20 passes through 12 states.

Those states are Massachusetts, New York, Pennsylvania, Ohio, Indiana, Illinois, Iowa, Nebraska, Wyoming, Montana, Idaho, and Oregon.

How long is Route 20 in MA?

Route 20 is 153 miles in Massachusetts.

How long is Route 20 in NY?

Route 20 is 372 miles in New York.

How long is Route 20 in PA?

Route 20 is 45 miles in Pennsylvania.

How long is Route 20 in OH?

Route 20 is 261 miles in Ohio.

How long is Route 20 in IN?

Route 20 is 156 miles in Indiana.

How long is Route 20 in IL?

Route 20 is 234 miles in Illinois.

How long is Route 20 in IA?

Route 20 is 300 miles in Iowa.

How long is Route 20 in NE?

Route 20 is 432 miles in Nebraska.

How long is Route 20 in WY?

Route 20 is 522 miles in Wyoming.

How long is Route 20 in MT?

Route 20 is 10 miles in Montana.

How long is Route 20 in ID?

Route 20 is 411 miles in Idaho.

How long is Route 20 in OR?

Route 20 451 miles in Oregon.

What cities does U.S. Route 20 go through?

Along with its starting city of Boston, Massachusetts, U.S. Route 20 passes through, or on the outskirts of, multiple large cities. (For the sake of this article, we’re defining large cities as those with 100,000 or more residents.)

Those cities are:

  • Springfield, MA
  • Buffalo, NY
  • Cleveland, OH
  • Toledo, OH
  • South Bend, IN
  • Chicago, IL
  • Rockford, IL
  • Boise, ID

U.S. Route 20 also passes through multiple smaller cities, including:

  • Waltham, MA
  • Albany, NY
  • Erie, PA
  • Gary, IN
  • Dubuque, IA
  • Waterloo, IA
  • Sioux City, IA
  • Casper, WY
  • Idaho Falls, ID
  • Bend, OR
  • Albany, OR
  • Corvallis, OR

Other notable places U.S. Route 20 passes include:

  • New York’s Finger Lakes Region
  • Lake Erie
  • Indiana Dunes National Park
  • Lake Michigan
  • The Mississippi River
  • Yellowstone National Park
  • The Continental Divide
  • Craters of the Moon National Monument
  • Boise National Forest
  • Willamette National Forest

In Yellowstone National Park, U.S. Route 20 doesn’t just pass through.

It’s the park’s main road.

You can only access the route by paying to enter the park, and it’s closed for five months of the year (December-April).

Is Route 20 the longest road in America?

Yes. At 3,365 miles, Route 20 is the longest road in America.

It is longer than the longest interstate in America, Interstate-90, which is 3,021 miles.

Does Route 20 go coast to coast?

Not quite, but it comes very close to it.

Route 20’s eastern terminus is about 3 miles inland from Boston Harbor at Kenmore Square in Boston and it’s western terminus is half a mile inland from the Pacific Coast in Newport, Oregon.

So, it’s not quite coast to coast (the eastern terminus could stretch a little closer to the water).

But it does cover the entire route between two coastal cities.

What is Route 20 called?

Not to be out-nicknamed by the “Mother Road” Route 66, Route 20 has several nicknames in different regions of the U.S.

Just west of Boston, it’s known in parts as “Southwest Cutoff” and “Hartford Turnpike.”

In the Berkshires, the route is called “Jacob’s Ladder Trail.”

Between Chicago and Rockford in Illinois, Route 20 is called “General U.S. Grant Highway.”

Through Montana, it’s called “Targhee Pass.”

Route 20 also shares some segments with other roads, including US-26, I-25, and I-84.

So, wherever you are in the country, U.S. Route 20 may be called by another name, but it is still one continuous route.

How long does it take to drive Route 20?

With speed limits (and traffic) factored in, it takes at least 60 hours to drive Route 20.

At eight hours/day, that’s a full week+ of driving.

But we recommend budgeting 70-75 hours just for the drive (with fuel stops, food stops, and toilet breaks) alone. (You’ll encounter quite a backup through Yellowstone if you choose to follow the route all the way through.)

And there you have it. U.S. Route 20 is America’s longest highway and its longest road.

Want to know about the country’s longest interstate, see What Is The Longest Interstate In The U.S.?