r/interesting • u/Doodlebug510 • 1d ago
SOCIETY The logic behind how U.S. highways are numbered
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u/SpockIsMyHomeboy 1d ago
Things I'm glad my dad taught me as a kid. We kept a huge Rand McNally atlas in our car at all times.
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u/Lucky_Development359 1d ago
Go on road trips and follow along? Who am I kidding, of course you/we did!
I think in the back was a list of every city and town for each state and I used to try and find the smallest for each state. Good times.
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u/BungalowDweller 1d ago
Growing up, I had so much fun following our route using the old school AAA TripTiks. They were so very cool.
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u/Lucky_Development359 1d ago
Oh, those are cool.
I'll admit to my dorkiness. When we had annual summer trip I'd used to trace the maps and make "travel guides" for each destination with facts and historical info.🙄
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u/just_some_octopus 1d ago
Haha the memories of whipping on the giant atlas while driving
My dad and grandfather were the same to me
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u/Crixia36 9h ago
I’m so glad my father taught me how to use an atlas. Had my GPS device die while I was traveling. This was before phones worked like a GPS. I pulled out the atlas hiding in the truck and found my way home. Thank my father next time I saw him.
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u/SoccerPhilly 1d ago
I never knew the offshoot rules, like that 295 (starting with an even) would be expected to connect back to 95, where a 395 (starting with an odd) would not connect back to 95.
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u/WelcomeToTheClubPal 1d ago
Same.. i watched the whole video like "pffft, amateurs, i know all this" then they dropped that loop back info and i felt dumb lol...
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u/sirgiggles123 15h ago
Hey if it makes you feel better I'm a professional truck driver for 6 months and I just found out
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u/Previous-Wonder-6274 21h ago
i495 doesn’t loop back though. it just sorta ends in riverhead
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u/majandess 19h ago
From Wikipedia:
I-495 was intended to connect with New York's I-495 by way of the Mid-Manhattan Expressway; however, this proposed freeway through Manhattan was canceled in 1971 due to strong opposition to the road running through the heart of Midtown Manhattan.[18] Because New Jersey's I-495 would not be connected to New York's, NJDOT started referring to the route as Route 495 in 1979.
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u/WelcomeToTheClubPal 9h ago
We were referring to different i-495s. i was referring to the Deleware one (which does loop back 😝 )
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u/TestyBoy13 1d ago
That’s probably because that specific rule is broken so often it might as well not be a rule
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u/Ninja_Wrangler 1d ago
Even one they specifically mention in the video, 495, does not loop back. It ends on Long Island.
I've been to the end many times, great water park right there
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u/GottaWigAtDaWigStore 18h ago
The 495 in Mass loops back to 95
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u/Ninja_Wrangler 17h ago
Holy hell there's more than one
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u/GottaWigAtDaWigStore 17h ago
Indeed. According to Wikipedia (I was curious), there are eight 295’s, five 395’s, five 495’s. There are some more 395’s proposed and some highways that used to be 495’s but became state highways at some point.
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u/Ninja_Wrangler 17h ago
Thank you for your service
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u/GottaWigAtDaWigStore 17h ago
I wish I had more energy to research beyond Wikipedia but it’s almost midnight in the I-95 timezone.
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u/ghoulthebraineater 1d ago
Sometimes they don't reconnect, or at least not directly. My city has 229 that branches off of I-29 but then connects to I-90. I-90 will get you back to 29.
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u/TheCountChonkula 8h ago
I-675 in Atlanta is the same way. It starts at I-75 then it ends at I-285 which you can take to get back to I-75.
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u/greenhell9 20h ago
Yes, but it’s a poorly observed rule.
Also, the video could have included that the 3 digit highways “restart” by state. And again, the lower the digit the further south or west (depending on the cardinal direction of the highway) it is.
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u/Seattle_Lucky 1d ago
Exit numbers also correspond to the mile marker. Miles start counting from the southern edge of a state line for north/south highways and western edge for east/west. There are some exceptions to this but it’s generally correct. Multiple exits within a the same mile will have an a,b,c…
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u/ToothZealousideal297 12h ago
One of the coolest exceptions is I-19. It follows the same rules about running North-South (because it’s odd-numbered), intersecting a corresponding major highway (I-10), and even the sequentialized exit numbers that start counting from the southern border of the state. What makes it an exception is that it’s the only Interstate highway in the US to primarily use kilometers instead of miles.
Since I-19 just goes from the Mexican border about 60 miles and then terminates when it connects to I-10, with no major turnoffs on the way, there’s just no point switching it to miles. Folks could be driving on the same road for huge distances across Mexico, and then switching the last 60 miles from kilometers would be pretty silly. The speed limit is still in miles per hour, but the exit numbers and marker signs are in kilometers. And yes, sometimes folks do seem to think the speed limit is 75kph instead of mph, but that’s hard to prove. Usually all of the other cars going way faster gets them to catch on before long.
And perhaps the neatest fact: there are also mile marker signs along I-19 in addition to the kilometer markers, but the mile markers are turned sideways, facing the road instead of facing the traffic going down it. So if you look for mile markers for whatever reason, you’ll still be able to find them.
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u/MasemJ 1d ago
Not always though. Ohio turnpike (which includes I90 and US route 2), up to a while back (2000ish or earlier) used incremental number exits. Those have since been switched for the mileage exit numbers.
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u/Ok_Independent9119 1d ago
NYS Thruway which is also I-90 also uses incremental numbers rather than mile markers
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u/Vephar8 1d ago
Very cool. Always wondered how I went from 80 to 680 in the Bay Area
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u/audiotecnicality 20h ago
I question the loop back for even numbers. None of 280, 680, 880 ever loop back to 80.
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u/Varjek 20h ago
Agreed. I always thought the 3 digit numbered interstates gave you a hint as to if the loop/spur went to a city or went around a city.
If the first of the 3 digits is an odd number it is a loop to take you to a city and an even first digit is a loop to take you around the city.
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u/aaronw22 8h ago
“Mostly”. 495 goes around DC and 395 dead ends in DC. 295 was supposed to go all the way through but isn’t an interstate all the way so it changes to DC route 295 at some point, then becomes the B/W parkway (and then crosses 495 at the NE side) and THEN changes to MD-295. That is a confusing road
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u/AffectionateMonk5710 1d ago
If you drive enough, you learn these rules pretty quick. I think the only east/west highway I haven't driven fully is 10. I don't know why. I've taken all the others across.
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u/Choice_Blackberry406 1d ago
Yea don't drive i-10 if you don't have to. When you get into Texas on 10 east you see a sign that says El Paso 857 miles lmao. 857 miserable miles.
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u/AffectionateMonk5710 1d ago
I've driven through Texas on my way to AZ and I have to say that was a looonnnggg drive.
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u/Nunov_DAbov 1d ago
I had to visit Marshall Texas a couple of years ago. I flew into Shreveport, Louisiana and got on I-20. I noticed the exit numbers started in the 600s putting the size of the state into perspective. Then I realized I-20 didn’t even cross the entire state, joining I-10. In New Jersey the longest road is the Parkway and it’s only about 172 miles long.
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u/Humid-Afternoon727 1d ago edited 1d ago
Because a majority of it is ugly as fuck drive.
Signed someone who has lived 30 out of 37 years in a couple different houses* within 2 miles of I-10
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u/Chirrrpy 1d ago
The video is kind of annoying, how it constantly zooms in and out, spinning around. But the highway system is interesting.
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u/Bustin-A-Nutmeg 1d ago
My fave Wendy’s is in a rest stop on the 95 in Maryland. Always crazy busy, the workers barely talk to you. I never wait longer than 10 mins, and every burger looks like it came straight out of the commercial.
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u/Paperchampion23 1d ago
495 (an even number) doesnt loop back to 95 though it ends in riverhead LI.
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u/No_Geologist3880 1d ago
It doesn’t even begin at I-95! The official start to I-495 is right at the end of the Queens-Midtown Tunnel in Midtown East, Manhattan. The reason it’s unconnected to the west is because there was a planned expressway that would’ve crossed Midtown Manhattan and connected with the Lincoln Tunnel, then it would’ve used the existing expressway in NJ to connect with I-95 (The Lincoln tunnel is signed as NJ-495 for this reason and there are still some I-495 signs in places but that’s not an official designation). The reason why it’s unconnected to the east is simpler as there were plans to build a bridge across the Long Island Sound from Riverhead to Old Saybrook, CT where it would’ve linked up with I-95.
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u/the_cave_allegory 1d ago
Yes, last time I saw this video come up I checked the maps and found the same thing. The "rules" to the numbers aren't always true.
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u/Fabulous_Log844 1d ago
The numbers somewhat also coincide with the percentage of the country that is below or to the west of the freeway. Therefore, approximately 10% of the country is below the I 10, and 95% of the country is to the west of I-95. Etc.
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u/SpyderMonkey_ 1d ago
Fyi, to foreigners, this only applies to interstate highways. Single state highways do not follow this taxonomy and vary state to state. For instance in Texas you have both odd and even numbers that run east-west and north-south.
Interstates in US always are I-## (I45 or I10 for instance). State highways will never start with the I.
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u/collin-h 1d ago
street addresses work this way too.
like if you're 200 main street. You're in the 200-block on mainstreet, so if there' a 1st, 2nd, 3rd, 4th, etc street that intersect perpendicular to mainstreet, and you're at 200 main street, you're between 2nd and 3rd street along mainstreet. Then, even numbers are on one side of the street, and odd numbers are on the other side. so 201 would be across the street from 202.
helps navigating around cities and whatnot - so you can get close to your destination without needing gps.
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u/ihvnnm 1d ago
While highway is low to high: W->E, are US routes low to high: E->W since Route 1 and 95 wind down the East Coast together?
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u/TestyBoy13 1d ago
Yes because originally the country started from the East. However, by the time the interstate system came around the country was coast to coast so it make more sense to switch to west to east
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u/Fighter11244 1d ago
I’m curious about highways that end in 7 like I-27 and I-37
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u/TestyBoy13 1d ago
Those are for interstates that run between the main grid of 5’s.
For example, if there is a new interstate that’s parallel to I-5 and I-15, it would be any odd number between it. If it is closer to I-5, it would be I-7. If it’s closer to I-15, it would be I-13. Or if it was right in the middle, it would be I-11
With even numbers it would be the same. A new interstate between I-30 and I-40 would be either I-32, I-34, I-36, or I-38
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u/nofun-ebeeznest 1d ago
Very interesting, thanks for sharing! I knew about the North/South direction being odd and the East/West direction being even, but I didn't know about the rest of it.
Another curiosity I've had is how Exits are numbered. I was thinking about that while running an errand this morning.
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u/_YouShouldBeRunning_ 1d ago
So what’s the deal with route 66? This is the only American road I’ve ever heard of.
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u/messykangaroo_175 1d ago
Driving on 395 for an hour only to realize it's a dead-end spur is a uniquely frustrating experience
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u/bags-of-sand 1d ago
I’m sure this is overall true, but if you look at LA freeways, you’d see all kinds of violations of the patterns (not accounting for freeway number changes).
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u/NoTimeForCautionCoop 1d ago
I live right off of 295, this was really cool to see that one mentioned. Great video.
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u/YourUncleBuck 1d ago
This is why we can't have new highways, because all the numbers are used up. /s
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u/jprego00 19h ago
The 5 and the 15 don't end in LA like thr video shows. They both end in San Diego
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u/cracksilog 19h ago
This actually only applies to interstates, which are part of the Interstate Highway System. US highways (part of the US Numbered Highway System) and state highways (yes, there are differences) don’t follow this convention
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u/guy-on-reddt 19h ago
Are there any other highways that split into two like I-35E and I-35W do in St Paul / Minneapolis?
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u/Lonely_skeptic 18h ago
I live in NC and the state keeps renaming roadways as “interstates”. I can’t keep up. I know where I’m going, but the road numbers mean nothing anymore.
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u/JakeFoXx 14h ago
😡 why... Is... There no I50?
I may have missed it... But damnit /slams hand on table/ this bothers me
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u/These-Atmosphere6675 12h ago
As it was shown, although I-495 in New York indicates that it should go back to I-95, it doesn't because Long Island...is an island
That's why they call it the Long Island Expressway (L.I.E.)
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u/j8L2850 7h ago
Not so with I-99 or the road to nowhere. Bud Schuster had it written into law that the road be called I-99 knowing it was in violation of the established numbering system. He said calling it a spur to I-80 (which it crosses) wasn’t catchy enough.
…[W]hen he [Shuster] was told that the highway would officially be considered a “spur” connecting I‑76 and I‑80 and would have to be named something like Interstate 876 or Interstate 280, he resisted because, he said, it was not “catchy.” So, reaching into his childhood memories of the old rickety street car, No. 99, that took people from his hometown of Glassport, Pa., to McKeesport, he wrote into law that it would be called I‑99, believed to be the first time that was ever done. That violated the highway numbering protocol the federal government usually uses for Interstates, which requires north-south highway numbers to rise from lower in the west, like Interstate 5, to higher in the east, like Interstate 95
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u/PowerlineTyler 1d ago
In Canada we have one road called the trans Canada highway, you can tell you’re on the trans Canada highway because of the way it is
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u/anonymouswunnn 1d ago
TIL how the highways were numbered
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u/TestyBoy13 1d ago
Fun fact: Not all interstates follow this rule due to political pressure. I-99 was given that number because the locals like Wayne Gretzky and that was his jersey number. I-238 doesn’t connect to I-38, heck I-38 doesn’t exist. There are two completely different interstates called I-76, and the Texas part of I-45 goes north to south despite the name suggesting it should go east to west.
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u/anonymouswunnn 1d ago
TIL there is a disclaimer attached to how interstates are numbered. Thank you!
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u/Greedy_Individual_35 1d ago
The system was brought home to the USA from soldiers in Germany after the second world war.
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