81 on 81

I’m planning a quick trip down to southwestern Virginia and neighboring West Virginia, intending to count some new counties along the way although primarily for other purposes. I wish I could say it was entirely about the counties and I could finally finish Virginia. That will have to wait for another day.

Being true to my nature, I’ll completely over-prepare with multiple maps, both electronic and paper, even though I’ve driven the vast preponderance of the route multiple times and understand it intuitively. I’ll have lat/long coordinates prerecorded in my GPS, turn-by-turn directions printed from my preferred map website, and a battered dogeared Triple-A road atlas as a backup should a solar flare destroy every navigational satellite and should an asteroid bust the car window and suck the printouts from the dashboard. Nobody will be getting lost. No way, no how. Logic has no bearing here. Preparations will be ridiculous.

Patterns often appear on 12MC and another one emerged as I plotted waypoints. Most of the path involved Interstate 81, the primary route along the western diagonal of Virginia (map). Many of those waypoints fell awfully close to longitude 81 West. This type of reasoning often leads me to trouble. Was there a place, I wondered, where 81 West crossed Interstate 81? It seemed like it would offer a nice bit of numerical symmetry.

In fact a golden spot existed at 36.938110°,-81.000000°, just a stone’s throw from the Wilco Hess Truck Stop – Wytheville. Or the Flying J. Or Galewinds Go Carts & Mini Golf although apparently it’s closed now so scratch that suggestion.

Were there other Primary (e.g., one or two-digit) Interstate Highways equally blessed with similar golden spots? Why yes there were. Longtime readers already knew that I’d have to map them.

View Interstate-Coordinate Confluences in a larger map

I noticed that spots concentrated in the eastern half of the nation, many in the Upper Midwest. I think I found all of the possibilities although there might be others lurking out there. Let me know if you find any that I overlooked and I’ll add them to the map.

Interstate Longitude Confluences

Chicago Skyline During Sunrise from Lombard, Illinois
Chicago Skyline During Sunrise from Lombard, Illinois by Corey Seeman, on Flickr
Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic (CC BY-NC-SA 2.0)

Longitude possibilities were limited to feasible values between 67 (easternmost whole number longitude) and 99 (highest possible 2-digit Interstate Highway). I found a total of seven places where a longitude crossed an Interstate highway with the same number, including the original example I discovered on I-81.

Some of those spots saw more traffic than others although I’d be surprised if even a single person recognized the significance. Why would they? Only a geo-oddity aficionado would find the topic even mildly interesting. One such location fell in Lombard, Illinois, a suburb of Chicago. I was surprised to find a photo of the Chicago skyline captured from an upper floor of a hotel less than a mile away from I-88/88°. That amused me for some weird reason.

Interstate Latitude Confluences

Lincoln Village, Milwaukee County, Wisconsin

There were fewer latitude opportunities, limited to values between 25 (southernmost whole number latitude in the Lower 48 states) and 49 (northernmost). I found only two occurrences.

Once again I was lucky to find something to illustrate a nearby area, the Lincoln Village neighborhood in Milwaukee, Wisconsin. I-43 formed its eastern boundary including the segment with I-43/43°.

The overall champion had to be Interstate 94. It shared a confluence with longitude 94° West. It was also concurrently signed with a stretch of I-43/43° North and I-90/90° West.

Confluences Outside of the United States

Penllergaer by stu, on Flickr
Creative Commons Attribution-NonCommercial-NoDerivs 2.0 Generic (CC BY-NC-ND 2.0)

Similar confluences existed outside of the United States. I found a couple of occurrences between motorways and longitudes in the United Kingdom. One fell near a lovely waterfall at Penllergaer Valley Wood (M4/4° West).

I even discovered one in Ireland, M8 and 8° West: 52.356181°,-8.000000°.

Then I grew tired of the exercise.

7 Replies to “81 on 81”

  1. Looks like there’s no longitude intersections in Russia, at least with M roads (I hadn’t checked the entire network, but essentially everything is too far east).
    Several different latitude ones though, all of which are in Siberia (one appears to be within the city of Gorno-Altaysk, all the others I found are basically middle of nowhere).

  2. As an unabashed ‘Degree Confluence Nerd’, I love stories like this. BTW, the numbers of U.S. interstates can go above 99, because some ‘spur freeways’ are numbered with a 3rd (i.e., ‘hundreds’) digit. That would make it theoretically possible for such a freeway (numbered in the range 100-124) to intersect one of lines of longitude in the western U.S. Unfortunately, however, I couldn’t find such an example. The closest that I found was I-115 that runs near Butte, Montana (at about 113 degrees West).

  3. No such luck in Germany, at least not among Autobahns.

    But two near misses!

    One is on the A8, which is discontinuous, with a gap through a large forest, where the State Road 10 joins the two ends; it’s State Road 10 that passes though 8° E at around 49.21835, 8.0000.

    The other is on the A51, which was planned but never built. Going by the description on the Wikipedia page, if it had been built along the planned route, it would definitely have crossed 51° N, probably somewhere in the vicinity of 51.000, 6.2647.

    (There were also several roads in the range 6 to 15 which came within 1° of their respective meridian.)

    1. Among German Federal Roads, B7, B8, B10, and B12 cross their respective meridians, and B51 crosses its parallel.

      B50 just barely misses it; one stretch which was downgraded to State Road (since a highway running in parallel had rendered that stretch obsolete as Federal Road) passes through 50.0000, 6.8023 and 50.0000, 6.8107, while Federal Road 50 itself comes as close as 49.9898° in one point and 49.9990° in another.

      (Incidentally, my previous comment should have read “Federal Road 10” (Bundesstraße) instead of “State Road 10” (Landesstraße).)

      1. For what it’s worth, A6 in Luxembourg crosses the 6th meridian (near Capellen). Only integer parallel crossing Luxembourg is the 50th; doesn’t look like there’s any road 50 nearby.
        No integer parallels or meridians appear to pass through Liechtenstein, Monaco, San Marino, Andorra and Vatican City, so that’s it for the European microstates, unfortunately.

  4. You could also look at U.S. Highways. U.S. 40 crosses the 40th parallel at least three times: 79°51’18.0″, 81°41’20.4″, 105°54’07.2″W. Given the numbering system for the U.S. Highway system I suspect the 40 is the only east-west highway to cross its parallel and that no north-south highway crosses its meridian, but there are probably several north-south highways in the 30s and 40s that cross their parallel and several east-west highways in the 70s, 80s, and 90s that cross their meridian.

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