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North, south, east, west — which direction does U.S. Highway 20 really run?


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IDAHO FALLS – When reports on crashes along U.S. Highway 20 — one of the biggest complaints we get is that we refer to the highway as westbound or eastbound.

On Sunday, for instance, we reported on a fatal crash involving a van and a semi truck on U.S. 20 near Rexburg. We reported the crash was in the westbound lane, and that all traffic was being diverted.

RELATED | Local man dead after van crashes into semi-truck

A short time after that story was posted, an user reached out to us, saying the crash occurred in the southbound lane.

“There is no westbound lane,” he wrote.

We get similar comments anytime we report on something that happens along this route, so we would like to clear up any confusion surrounding this issue.

First of all, it’s true that in eastern Idaho, U.S. 20 does run north and south, but nationwide, the road is actually an east and westbound route. The red line in the map above shows the route the highway follows.

“The longest portion of U.S. 20 running north and south is in eastern Idaho,” Megan Stark, a spokeswoman for Idaho Transportation Department, tells “It will obviously run north and south a teeny bit (in stretches throughout the country), but eventually it levels out.”

Most of the federal and state agencies — including Idaho State Police and the Idaho Transportation Department — use the term “eastbound” and “westbound” when referring to U.S. 20 in news releases to media. For a while, we tried correcting every release to the direction that stretch of road is traveling where an accident happens, but that inevitably leads to more confusion and frequent errors if our terminology does not match that of traffic officials.

A federal law designates all odd-numbered national highways as north and south, and all even-numbered highways as west and east. When the numbered highway system was conceived in 1925, state and federal highway officials “decided that numbers ending in zero would be assigned to the transcontinental or major east-west routes,” according to the Federal Highway Administration.

So officially, there is a westbound lane near Rexburg, but it does not run west in that area. When we say a wreck occurs in the westbound lane, it is correct, but it is the lane you think of as southbound. Or if it’s the eastbound lane, it’s the lane you think of as northbound.

West = South, East = North. Get it?

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Sign posted in Newport, Oregon, at entrance of U.S. Highway 20. | Robert Patten,