Interstate Highway Counties

On January 31, 2016 · 13 Comments

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

It occurred to me that I will need to hit backroads a lot more often as I fill in the blanks and doughnut holes in my personal capture map. Those 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. It wasn’t a question that demonstrated any greater practical purpose although that never stopped Twelve Mile Circle from going down a rabbit hole before. It wasn’t completely pointless I rationalized, because the results could be used to separate the "easy" counties from the more difficult ones, roughly speaking. Amateur county counties 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 the mythology of not being able to truly appreciate the United States until exiting the highways.

Naturally, 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.

Counties with Interstate Highways

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 fnished it — although 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.

One of the features of Mob Rule that I’ve enjoyed over the years is its simple statistics to catalog counties visited by state. It produced 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 because I didn’t feel like typing them out. Wikipedia provided a nice cross-reference. I sorted states by percentage completed from highest to lowest although one could rearrange the table in reverse order, alphabetically, or whatever might be desired and it won’t harm the underlying document.

Some observations jumped out. For example, county counters who stuck solely to Interstate Highways wouldn’t even visit 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 it was considered both a state and a county for county counters (in reality neither) because it was such a specialized case. Discounting that, Interstate Highways served 7 of 8 counties (87.5%) in Connecticut for the top spot, ranging 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, hitting above 70 percent.

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 weren’t signed as Interstate Highways (I included all of the so-called Secret Interstates too).

However, I’d been unaware of the bizarre disconnected set of Interstate Highways in the southernmost tip of Texas, Brownsville and McAllen. They formed 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, which nobody would ever do because it would be absurd.

I enjoyed the exercise even if it didn’t serve much of a useful purpose. It did confirm to me that Interstate counties were visited more frequently in general than non-Interstate counties, not that there was an underlying controversy. That could be observed quite easily when comparing the map I created with Mob Rule’s composite map of all county counters. The patterns looked strikingly similar.

On January 31, 2016 · 13 Comments

13 Responses to “Interstate Highway Counties”

  1. Andy says:

    Much like the composite map you posted, Mob Rule also has composite maps for each state, such as:

    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 says:

    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.


  3. KCJeff says:

    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.

  4. wangi says:

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

  5. Peter says:

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

  6. Steve Spivey says:

    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 says:

    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.

  8. Scott Surgent says:

    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.

  9. Scott says:

    Here’s a 1319 mile route where the Google Maps default route goes on 0 Interstate highways.
    Is there anything longer?

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