Interstate Highway Counties

I requested an additional account on the Mob Rule county counting website recently. I’d been planning a couple of trips for 2016. This including one focused primarily on adding new counties to my lifetime tally in an obscure geographic corner of Appalachia. So I’d been using this spare account to calculate “what-if” scenarios. Naturally, I didn’t want to disturb my existing map in the process so a second account came in handy. Twelve Mile Circle readers will likely see maps generated by this account in the future as I chart further adventures.

Then it occurred to me that I will need to hit back roads a lot more often. That’s the only way I’ll ever fill in all the blanks and doughnut holes in my personal capture map. Those efforts will diminish my pace although they will also allow me to experience out-of-the-way places where few people tread.

It made me wonder exactly how much of the United States one would miss using only the Interstate Highway System. Really, this wasn’t a question that demonstrated any greater practical purpose. But that never stopped Twelve Mile Circle from going down a rabbit hole before.

It wasn’t completely pointless I rationalized. I could use the results to separate the “easy” counties from the more difficult ones, roughly speaking. Amateur county counters would stick primarily to the Interstate Highways while the truly dedicated hunters such as myself would need to veer into the empty white spaces. I supposed it made me feel more serious about my pursuit by separating me from the pack. It fed into a mythology. Can one truly appreciate the United States unless one ventures away from the highways?


Drawing the Map

So I began by making a map of counties served by Interstate Highways, both two-digit and three-digit. Readers would probably want to open the image in another tab to get the full-sized image.

U.S. counties with Interstate Highways. Map generated by mob-rule.com

I couldn’t guarantee that I marked every county served by an Interstate Highway because I created this manually. I was still finding new ones that I’d missed hours after I thought I’d finished it. Even so, this should be close. Please feel free to offer corrections and I’ll update the map. For those wondering about the odd title, “Travels of T. H. Driver, ” that was simply my initials plus the word Driver. I had to give the dummy account a name and that seemed as good as anything.

Mob Rule includes a lot of features that I’ve enjoyed over the years. One involves simple statistics to catalog counties visited by state. It produces a nice summary table of counties visited and percentages of states covered. I placed those data into a Google Docs Spreadsheet that readers should feel free to review if interested.

Mob rule assumed everyone knew the 2-letter postal code abbreviations for each state so I can’t help you if you don’t know them. I didn’t feel like typing them out. Wikipedia provided a nice cross-reference though. I sorted states by percentage completed from highest to lowest. However, one could rearrange the table in reverse order, alphabetically, or whatever direction one might desire. Go ahead and try it out. It won’t harm the underlying document.


Winners and Losers

Interstate 395 - Washington D.C. Photo by Doug Kerr; (CC BY-SA 2.0)
Interstate 395 in Washington, DC

Some observations jumped out. For example, county counters who stuck solely to Interstate Highways wouldn’t visit even half of the counties in the United States. The total would hit 44% but who’s counting? The chart also sifted winners from losers. I discarded the District of Columbia’s 100% although county counters considered it both a state and a county for their purposes (in reality neither). So, discounting that, Interstate Highways served 7 of 8 counties (87.5%) in Connecticut for the top spot. Then it ranged all the way down to 16 of 77 counties (17.2%) for Nebraska at the bottom.

Results followed intuitive patterns. Small northeastern states with large populations contained numerous Interstate Highways. Large, expansive Great Plains states with smaller populations featured fewer of them. New York and Pennsylvania posted particularly impressive results given the number of counties contained within each of them. Both punched above 70 percent.


Anomalies

Of course there were some anomalies.

  • Someone would likely mention the paradox of Interstate Highways in Hawaii so I’ll simply link to the Federal Highway Administration’s explanation (i.e., “the Interstate System is more than just a series of connected highways. It is also a design concept“) and get that out of the way.
  • The same condition existed in Alaska although the roads didn’t feature Interstate Highway signage.
  • Additionally, I included all of the so-called Secret Interstates for the sake of completeness.
The Interstate 2 Split. Photo by Jimmy Emerson, DVM; (CC BY-NC-ND 2.0)
Interstate 2 in Texas

However, I didn’t know about the bizarrely disconnected set of Interstate Highways in the southernmost tip of Texas until now. Those exist between Brownsville and McAllen (map). They form a rough U-shape, outlined by I-69E, I-2 and I-69C (for central?). One would need to hop a plane or drive through Mexico to capture these Interstate counties without disturbing non-Interstate counties surrounding them. Nobody would ever do that because it would be absurd. Or would they?

I enjoyed the exercise even if it didn’t serve much of a useful purpose. It did confirm in my mind that people visit Interstate counties more frequently in general than non-Interstate counties. But that’s not particularly insightful or controversial. One can observe that quite easily by comparing the map I created with Mob Rule’s composite map of all county counters. The patterns looked strikingly similar.

Comments

13 responses to “Interstate Highway Counties”

  1. Andy Avatar

    Much like the composite map you posted, Mob Rule also has composite maps for each state, such as: http://www.mob-rule.com/view/OH/all

    Those maps help to enhance the sense of accomplishment when successfully recording a visit of a county that shows up at the bluer/whiter end of the scale.

    My only complaint? I’d love to see actual numbers for each county, rather than just an undefined scale of colors.

  2. Ben Avatar
    Ben

    As far as I can tell, I-69C does in fact stand for Central, as there is an I-69W that runs for about a mile and a half in Laredo (at least according to Wikipedia). That whole I-69 mess is quite interesting even outside of this context.

    hhttps://en.wikipedia.org/wiki/Interstate_69W

  3. KCJeff Avatar
    KCJeff

    Missed 1 in MO. I-72 crosses the Mississippi River and terminates in Marion County, Missouri (Hannibal). Future plans have it connecting to I-35 directly west, giving 4 more counties interstate access.

    1. Twelve Mile Circle Avatar

      Good catch! I’m not sure I would have ever noticed that little spur. I’ve updated the graphic and the spreadsheet.

  4. wangi Avatar
    wangi

    So, is there a list of the counties by hits… Which are the least visited?

    1. Twelve Mile Circle Avatar

      The closest that Mob Rule comes to that is found on the left column of the front page. It doesn’t have the number of hits though. It does list the most visited counties in the United States and Canada, and the least visited of the Lower 48 US States. I actually wrote a little blurb about that way back in 2011, "Least Visited U.S. Counties."

  5. Peter Avatar

    One interesting thing is that outside southern California most of the counties on the Pacific Coast are not served by Interstates.

  6. Steve Spivey Avatar
    Steve Spivey

    I notice there are barely any north/south Interstate roads in the center. One would hardly need any going from Amarillo, TX to Bismark, ND.

    An idea for a challenge, what is the longest DEFAULT route you can find on Google maps that doesn’t use any I-roads? (A quick check of Amarillo to any major city in ND has at least a tiny portion on it.)

  7. Joe Avatar
    Joe

    Mississippi County in NE Arkansas is missing. It is served by I-55.
    Alexandria County in extreme southern IL is missing. I-57 cuts through it around Cairo.

    I-69 is a major headache for this exercise as it is difficult to know what to count or not count. I just so happened to take a trip from St. Louis to Nashville and back this weekend and drove on a portion of I-69 that is now signed in Kentucky. Based on Wikipedia, it looks like a lot of the highway is completed and signed in Kentucky (thanks to overlap with existing roads) which would add a few Kentucky counties. Not sure about any other states along the proposed/future I-69 corridor, although of course Texas was mentioned above.

    1. Twelve Mile Circle Avatar

      I’ve added the first two. I think I’ll wait a little while for I-69 to sort itself out though.

  8. Scott Surgent Avatar
    Scott Surgent

    Add Santa Cruz County (AZ) to your map. It’s the little county at the very south edge of Arizona. It is served by Interstate-19, which runs north from Nogales to Interstate-10 in Tucson. I-19 is one of very few highways in the nation to be reckoned in kilometers.

    1. Twelve Mile Circle Avatar

      Apparently I missed quite a few. Hopefully I’m getting close to cleaning this up!

  9. Scott Avatar
    Scott

    Here’s a 1319 mile route where the Google Maps default route goes on 0 Interstate highways.
    https://goo.gl/maps/y2qKd2bRBkn
    Is there anything longer?

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