Marking the miles

June 25, 2008

(Today’s quiz: What’s the distance from the Fort Wayne Airport Expressway exit of 1-69 to the I-465 exit in Indianapolis?)

Outside of Fort Wayne, the road I travel on the most is I-69, to visit my sister in Indianapolis once or twice a month. Driving it (as I did this past weekend) gives me an appreciation of one thing Indiana gets right. Some states (such as New York) number their interstate exits consecutively, without regard to any outside factor — Exit 1, Exit 2, Exit 3, etc. But some states (such as Indiana) do it a better way: The exits are numbered according to the mile marker they are at or closest to. So, heading south, you go from Exit 64 (Marion) directly to Exit 59 (Gas City). Heading north, Exit 14 (Fortville) comes immediately after Exit 10 (Noblesville).

If you’re driving on an interstate in New York and see that you’re at, say, Mile Marker 55, all you know is that you’re 55 miles from one end of the highway. (Tip of the day: All interstate mile markers start at the southern or western end of the road; numbers get higher as you go north or east.) But if you see that you’re at a certain mile marker on I-69, you also know what exits you’re near. And if you happen to see an exit, you don’t have to have been paying attention to the mile markers to know how far along the trip you are. This is a tremendous aid to people like me who are cartographically challenged (couldn’t find our you-know-whats with our hands and a flashlight).

Quiz answer: Exit 99 (here) to Exit 0 (there), the perfect 100-mile trip.


3 Responses to “Marking the miles”

  1. Doug Says:

    Do you suppose the New York roads are exempt because they were grandfathered into the Interstate system or maintained a little differently? I didn’t think the states, by and large, had control over Interstate signage.

    Most of the plain vanilla interstates in the various states use the mile-marker exit designation. The exception I have noticed is that some Toll Roads just number the exits consecutively. I’m pretty sure the Ohio toll road used to do it that way. For some reason an Oklahoma toll road is coming to mind as well, though I might be mistaken on that.

    I must’ve been in my mid-20s before I figured out the exit sign/mile marker relationship. I was surprised it had taken me that long.

  2. Leo Morris Says:

    According to this Wikipedia article ( ), states that still use sequential numbering include Connecticut, Delaware, Massachusetts, New Hampshire, New York, Rhode Island and Vermont. Maine, Virginia, Georgia and Florida. There’s also this fascinating tidbit: On I-19 in Arizona, length is measure in kilometers instead of miles, in part because it runs south to the Mexican border.

  3. Harl Delos Says:

    Did you know a loop is numbered clockwise, starting from the 6-o’clock position? I didn’t either, until just now, when I read the part of the MUTCD about exit numbering.

    The MUTCD is the Federal Highway Administration’s Manual of Uniform Traffic Devices. It says you can use either “reference location numbering” or sequential numbers. New York’s sequential numbers would be in compliance; the fact that they start numbering the thruway at NYC and end at I-90 would not.

    (Insert joke about New Yawkers being backwards here.)

    Supposedly Ohio converted to reference location numbering about 1973 and Indiana about 1980. I remembered that I-69 had RLN in 1974, when I was working in Castleton, but my memory is known to lie, once in a while.

    Indiana is the only state NOT to have adopted the 2003 MUTCD (or written one of their own, as Ohio and 4 other states have). The deadline was December 22, 2005, and Indiana still uses the 2000 MUTCD. I don’t know whether to recognize that independence with a cheer or with a raspberry.

    Arizona isn’t alone in using kilometers; Delaware uses them on Route 1. If it runs to the Mexican border, I’d be surprised.

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