A lot of folks in the US take the Interstate System for granted, not knowing some of the smart features. I know for a fact that a lot of foreign visitors, first confused, think that our mile marker system tied to Interstate Exit numbers is brilliant (a lot more intuitive than other countries’).

Here is a quick breakdown of facts you may or may not know when hitting the open roads here in the United States:

Interstate and Highway Numbering (e.g. I-5 or I-90)
- ODD NUMBERS means it runs NORTH/SOUTH
- EVEN NUMBERS means it runs EAST/WEST

I-5 runs NORTH/SOUTH from California to Washington state.
I-90 runs EAST/WEST from Washington state to ??

* there are some exceptions to this rule but this is a majority and should be how Highways and Interstates are named.

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Mile Markers start from WEST to EAST or SOUTH to NORTH. For Interstates, they start over at each state line.

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Interstate Exits correspond to the Mile Marker. If there is more than one exit in a mile, it is appended an alpha (A, B, C, D) suffix in the order of appearance. Other countries simply start sequential numbering but you have no indication of distance between exit numbers.

If you just passed MM101 heading east (or north) and there is an exit before MM102, it will be Exit 101. If there are 2, the second exit you approach heading east or north will be 101B. This is in reverse obviously if heading west (or south) as the mile markers will be reducing each mile you travel towards the western or southern border of the state (or beginning of the Highway). If there is not another exit until MM104, the next exit will be Exit 104 (not 102 like in other countries).

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Signage: Where is your exit sign located?

Many people don’t know that depending on placement of the overhead exit notice, this indicates where the exit will occur. If the sign is to the right (most common), then you will exit the Interstate from the further right lane(s). If it is in the center, you continue your direction of travel and other routes will branch off. If it is on the left, you will exit from the furthest left lane(s).

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I’m sure I know more, but thought I would share these US driving tips for the unknowing resident and also foreign traveler. Enjoy! Also, if you know of any more tips, feel free to add more in the comments section below.

This entry was posted on Monday, July 24th, 2006 at 1:59 pm and is filed under Knowledge. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site. This post has been viewed 898 times.