I Never Knew: How Interstate Freeway Numbering Works

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Gary Leff is one of the foremost experts in the field of miles, points, and frequent business travel - a topic he has covered since 2002. Co-founder of frequent flyer community InsideFlyer.com, emcee of the Freddie Awards, and named one of the "World's Top Travel Experts" by Conde' Nast Traveler (2010-Present) Gary has been a guest on most major news media, profiled in several top print publications, and published broadly on the topic of consumer loyalty. More About Gary »

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Comments

  1. What are you, a Millennial? or Gen Zers? I’ve known how the Interstate numbering system worked since I was a kid and could read a map.

  2. C_M, you knew every single one of those rules and exceptions listed in the video, or you knew the basic ‘east-west’, ‘north-south’, bypass rules? Because I highly doubt you knew everything in that video when you were a kid.

  3. The old Rand-McNally US atlases explained the Interstate Highway numbering system in the first few pages. Don’t know if they still do.

  4. Except for I-99 – which was specifically numbered in the law that authorized the highway.

  5. @Tim L most people today don’t know that movie theaters once printed movie times in the newspaper and I bet a lot of younger people have never seen a road atlas 🙂

  6. I learned about the interstate numbering system as a young civil engineer. One thing he gets wrong is saying that the states decide what to name them, the Federal Highway Administration does that. He does leave off a ton of exceptions, but the video would be 20 minutes long to list them all.

  7. Easiest way I remembered direction of the highways were East-West are Even numbered. The same was usually true for flight numbers (even numbers for eastbound). It worked great for NWA’s routes out of NRT (correct me if I’m wrong).

    NW1 was BKK-NRT-LAX and NW2 was reversed LAX-NRT-BKK
    NW11 for DTW-NRT-SIN and NW12 for SIN-NRT-DTW
    NW19 for JFK-NRT-HKG and NW20 for HKG-NRT-JFK
    NW27 for CAN-NRT-HNL abd NW26 for HNL-NRT-CAN

    all the logic went out the door with DL merger.

  8. @craig – Yes, I knew all the basic rules. I didn’t know the exceptions because A. Unless you’re local, it’s not important and B. When I was a kid, most of those didn’t exist. When we started, even the major interstates weren’t complete. I-71 between Cleveland and Columbus took forever in the early 70s, because you still had to drive through every small town.

  9. @C_M None of the rules are important. This is all trivia. For practical purposes, the interstates could be numbered randomly. You came here to brag that you knew a bunch of obscure facts as a child. Craig called you out and now you’re embarrassing yourself with a lame explanation of your pompous boast.

  10. @Yin Jing – Always good to know @ayenus’ new moniker. I’ll just assume “Yin Jing” is Mandarin for “asshat”.

  11. I haven’t changed. Incredible to see a man who has been on this earth for the better part of half-a-century degrade himself into ad hominem and double down on self embarrassment. Mandarin is not written, it is spoken.

  12. Yin Jing:, at the risk (uh, more like a certainty) of unleashing a torrent of abuse of abuse from you here it goes: in the times I have been exposed to your “comments” (more like mini toxic screeds) you have been so negative, obnoxious or pompous (that vegetarian rant was so out of line on so many levels but to you that’s normal??!!) that I worry about your mental health. Do you own firearms? Do you have a drinking problem? I’m concerned about any humans that might cross your path and experience your unbridled anger. You have trashed this blog and it’s participants so stridently that I wonder why you are still on this site? If it’s that bad vote with your feet and walk away! You will make yourself as well as many VFTW participants very happy. I myself found dealing with the blog Your Mileage Will Vary
    (YMMV) extremely frustrating. The junior high school level writing (are editors extinct?), the excessive use of links (lazy), the constant rerun of old posts as new content (even lazier), the over reliance on reddit for blog material (lazy and sleazy) and the worst is censored comments to look good! Did I insult them and all those who participate and whose censored comments got posted? Did I tell them what to eat (uh, who does THAT?)? No! I walked away. Life is too short to let avoidable things bother you especially if you have anger management issues! Go life your best life you China bot you! And leave Mr. Leff alone please. We love his ethical behavior AND his typos!

  13. RE: The mysterious California “I-238” that breaks all of the numbering rules … The original roadway connecting what was designated California State Route CA-17 (now I-880) to US-50 (now I-580) used to be signed California State Route CA-238, and extends further south from the connector location. As CA-17 and US-50 were upgraded to Interstate Highway standards, the I-880 and I-580 designations replaced the older CA-17 and US-50 numbers, respectively. When the CA-238 connector section was upgraded to Interstate Highway standards, the California Department of Transportation convinced the Federal Highway Administration that changing the number from “238” to something else would confuse drivers, so I-238 was adopted for the 2.16 mile long connector.

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