What is the lowest exit number that doesn't exist anywhere in the US?

[KCRoadFan]

As is well-known among road fans, the highest exit number in the US is Exit 880 on I-10 in Texas, near the Louisiana border. However, there are many exit numbers below this one that do not exist on any freeway in the country (after all, not every number is represented by an exit on I-10 in Texas, as is the case with almost any freeway with distance-based exit numbers).

That brings me to my question: what is the lowest such number - that is, the lowest number that does not appear as an exit number on any freeway in the whole country. Obviously, the lower you go with the numbers, the more likely it is you will find an exit with that number, because there would be more roads available with mile markers in that particular number range.

If I had to guess, I'd probably say that the lowest number not appearing on an exit sign would probably be somewhere in the 400's range - I'm pretty sure it's in that range where there start to be substantially fewer opportunities for exits to have such a number, due to relatively fewer roads with mileages reaching such ranges. Can anyone unravel the mystery? (Perhaps we could choose individual numbers and try to find an exit with that number, and so on until we reach an exit number that we can't find. I think this would be a fun game!)

[ilpt4u]

If no one knows this off the top of their head, could turn this into a "Picture"  game, with the rules requiring it to be a US Exit Number, and see where we get derailed...

[Jim]

I don't claim this to be comprehensive, since they're all by me, and a few are international, but here's a bunch of numbers:

https://www.teresco.org/pics/signs/exits/

[webny99]

I don't claim this to be comprehensive, since they're all by me, and a few are international, but here's a bunch of numbers:

https://www.teresco.org/pics/signs/exits/

The first missing number appears to be... 270?

My guess is we'll end up somewhere in the 300's with the final answer, unless there really is no 270 anywhere.

[Scott5114]

I-40 exit 270 in McIntosh County, OK

Next up would be 280 and 281.

Someone should go back and check the Canadian numbers on Jim's page, though, just to make sure there's not an exit number that occurs in Canada but not the US.

[KCRoadFan]

Next up would be 280 and 281.

On I-44 in Missouri, Exit 280 is for Elm Avenue in Webster Groves.

[Jim]

TM data shows many Exit 281 examples.

Code Select Expand

AL/usai/al.i065.wpt:281 http://www.openstreetmap.org/?lat=33.800342&lon=-86.824887
AR/usai/ar.i040.wpt:281 http://www.openstreetmap.org/?lat=35.156754&lon=-90.127314
AZ/usai/az.i010.wpt:281 http://www.openstreetmap.org/?lat=32.006839&lon=-110.690174
AZ/usai/az.i017.wpt:281 http://www.openstreetmap.org/?lat=34.533076&lon=-111.966090
CA/usai/ca.i015.wpt:281 http://www.openstreetmap.org/?lat=35.468196&lon=-115.528746
CO/usai/co.i025.wpt:281 http://www.openstreetmap.org/?lat=40.755125&lon=-104.992518
CO/usai/co.i070.wpt:281 http://www.openstreetmap.org/?lat=39.774143&lon=-104.847121
KS/usai/ks.i070.wpt:281 http://www.openstreetmap.org/?lat=38.958041&lon=-97.111373
NC/usai/nc.i040.wpt:281 http://www.openstreetmap.org/?lat=35.890615&lon=-78.848619
ND/usai/nd.i094.wpt:281 http://www.openstreetmap.org/?lat=46.906712&lon=-98.227386
TX/usai/tx.i020.wpt:281 http://www.openstreetmap.org/?lat=32.471174&lon=-99.805008
TX/usai/tx.i045.wpt:281 http://www.openstreetmap.org/?lat=32.724259&lon=-96.762122
VA/usai/va.i064.wpt:281 http://www.openstreetmap.org/?lat=36.881748&lon=-76.213961
WA/usai/wa.i090.wpt:281 http://www.openstreetmap.org/?lat=47.652582&lon=-117.412992


[Jim]

Also, we had a game for this a while back that can narrow down this answer:

https://www.aaroads.com/forum/index.php?topic=17867.0

I can generate a list of all exit numbers as TM has them on the interstates pretty easily, but don't want to take too much of the fun out of answering this question.

[Ketchup99]

Next missing is Exit 285, but this is here: https://www.google.com/maps/@34.5513489,-111.9056831,3a,15y,15.87h,89.45t/data=!3m7!1e1!3m5!1sCcTu0ga06cc7aOvVQESxQQ!2e0!6s%2F%2Fgeo3.ggpht.com%2Fcbk%3Fpanoid%3DCcTu0ga06cc7aOvVQESxQQ%26output%3Dthumbnail%26cb_client%3Dsearch.revgeo_and_fetch.gps%26thumb%3D2%26w%3D96%26h%3D64%26yaw%3D303.0289%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192
Next 291, but it's here: https://www.google.com/maps/@38.9606405,-78.4429298,3a,49.5y,61.85h,94.7t/data=!3m6!1e1!3m4!1sqKQyv-2-JODE35UE5ROrqw!2e0!7i16384!8i8192
The list lacks a 295, but here's this in Portland, Oregon: https://www.google.com/maps/@45.4537779,-122.7172678,3a,18.1y,252.05h,94.59t/data=!3m6!1e1!3m4!1sHxrRqxLSF7ANI6Smbn6dkw!2e0!7i16384!8i8192
Next is 306... anyone have one?

[hobsini2]

Next missing is Exit 285, but this is here: https://www.google.com/maps/@34.5513489,-111.9056831,3a,15y,15.87h,89.45t/data=!3m7!1e1!3m5!1sCcTu0ga06cc7aOvVQESxQQ!2e0!6s%2F%2Fgeo3.ggpht.com%2Fcbk%3Fpanoid%3DCcTu0ga06cc7aOvVQESxQQ%26output%3Dthumbnail%26cb_client%3Dsearch.revgeo_and_fetch.gps%26thumb%3D2%26w%3D96%26h%3D64%26yaw%3D303.0289%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192
Next 291, but it's here: https://www.google.com/maps/@38.9606405,-78.4429298,3a,49.5y,61.85h,94.7t/data=!3m6!1e1!3m4!1sqKQyv-2-JODE35UE5ROrqw!2e0!7i16384!8i8192
The list lacks a 295, but here's this in Portland, Oregon: https://www.google.com/maps/@45.4537779,-122.7172678,3a,18.1y,252.05h,94.59t/data=!3m6!1e1!3m4!1sHxrRqxLSF7ANI6Smbn6dkw!2e0!7i16384!8i8192
Next is 306... anyone have one?

Exit 306 in Milwaukee.
https://www.google.com/maps/@43.0278391,-88.0253036,3a,75y,101.96h,87.43t/data=!3m6!1e1!3m4!1stzeVg6YMVRM-Vr1dycWdDw!2e0!7i16384!8i8192?hl=en

and the next missing number on I-94 is 313.

[Duke87]

We worked this problem out in Chat a few years ago and the answer is 535 511.

EDIT: Looks like I was misreading my notes.

[Ketchup99]

We worked this problem out in Chat a few years ago and the answer is 535.

Way to keep the game fun...

[NWI_Irish96]

We worked this problem out in Chat a few years ago and the answer is 535.

I-465 is 52.79 miles long, so if you do 10 full laps first, on the 11th time around Mann Rd would be exit 535.

[bassoon1986]

Next missing is Exit 285, but this is here: https://www.google.com/maps/@34.5513489,-111.9056831,3a,15y,15.87h,89.45t/data=!3m7!1e1!3m5!1sCcTu0ga06cc7aOvVQESxQQ!2e0!6s%2F%2Fgeo3.ggpht.com%2Fcbk%3Fpanoid%3DCcTu0ga06cc7aOvVQESxQQ%26output%3Dthumbnail%26cb_client%3Dsearch.revgeo_and_fetch.gps%26thumb%3D2%26w%3D96%26h%3D64%26yaw%3D303.0289%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192
Next 291, but it's here: https://www.google.com/maps/@38.9606405,-78.4429298,3a,49.5y,61.85h,94.7t/data=!3m6!1e1!3m4!1sqKQyv-2-JODE35UE5ROrqw!2e0!7i16384!8i8192
The list lacks a 295, but here's this in Portland, Oregon: https://www.google.com/maps/@45.4537779,-122.7172678,3a,18.1y,252.05h,94.59t/data=!3m6!1e1!3m4!1sHxrRqxLSF7ANI6Smbn6dkw!2e0!7i16384!8i8192
Next is 306... anyone have one?

Exit 306 in Milwaukee.
https://www.google.com/maps/@43.0278391,-88.0253036,3a,75y,101.96h,87.43t/data=!3m6!1e1!3m4!1stzeVg6YMVRM-Vr1dycWdDw!2e0!7i16384!8i8192?hl=en

and the next missing number on I-94 is 313.

Found a 313 near Baird, TX on I-20.


iPhone

[kphoger]

We worked this problem out in Chat a few years ago and the answer is 535 511.

EDIT: Looks like I was misreading my notes.

I keep reading about an Exit 511 on CA-1 (Daly City), but I'm unable to find an actual sign on Google.

[roadman65]

The OP said start looking in the 400's, but some freeways to make it to 500 plus with I-20 in Texas being at 635 miles in length and I-5 being even longer at 796.  So should it not be Exit 635  to Exit 796 then?

[hotdogPi]

The OP said start looking in the 400's, but some freeways to make it to 500 plus with I-20 in Texas being at 635 miles in length and I-5 being even longer at 796.  So should it not be Exit 635  to Exit 796 then?

Some numbers are skipped. Just because Exit 796 exists doesn't mean every number up to 796 does.

[MikeTheActuary]

We worked this problem out in Chat a few years ago and the answer is 535 511.

EDIT: Looks like I was misreading my notes.

I keep reading about an Exit 511 on CA-1 (Daly City), but I'm unable to find an actual sign on Google.

For southbound traffic, the south end of the I-280/CA-1 concurrency in Daly City has two exit numbers in the Cal-NExUS database:  280 Exit 47B, and CA1 Exit 511.   Exit 47B is what's posted per Google, and the Cal-NExUS documents indicate Exit 511 as merely "proposed".

If Exit 511 exists there, it does so only as a technicality.

CA 1 exits: https://dot.ca.gov/-/media/dot-media/programs/safety-programs/documents/exit/f0017832-1.pdf
I-280 exits: https://dot.ca.gov/-/media/dot-media/programs/safety-programs/documents/exit/calnexus-i-280-03-2020-a11y.pdf

[paulthemapguy]

I-80 in Nebraska has a 314
I-57 in Illinois has a 315
I-70 in Kansas has a 316
I-81 in Virginia has a 317
I-80 in Nebraska has a 318

[Duke87]

We worked this problem out in Chat a few years ago and the answer is 535 511.

EDIT: Looks like I was misreading my notes.

I keep reading about an Exit 511 on CA-1 (Daly City), but I'm unable to find an actual sign on Google.

Yeah, 511 exists on paper but isn't posted in the field. One of those CA exit numbers where none of the signs have been updated. May be posted in the future.

Interestingly, something similar happens with the next candidate up the list: there is no posted exit 529 anywhere, but internally this is the number for a rest area on I-10 in Texas.

So if you want the lowest that doesn't exist even on paper, the answer is 532.

All in all, the following numbers in the 500s are not posted anywhere in the US:
511
529
532
534
535
547
563
584
590
592
594
598

All of these exist internationally, however, so the highest exit number not posted anywhere in the world is over 600.

[KCRoadFan]

Are you sure that ALL of the numbers in the 400-499 range exist as exit numbers? Because somehow I doubt that.

(Although, I do suppose that I-35/35E through the Dallas area would capture the large majority of them...)

[Jim]

Are you sure that ALL of the numbers in the 400-499 range exist as exit numbers? Because somehow I doubt that.

(Although, I do suppose that I-35/35E through the Dallas area would capture the large majority of them...)

The only one TM's data for Interstates lacks in the 400s is 489.  But it does show an Exit 489 on US 101 in California.

[Duke87]

Are you sure that ALL of the numbers in the 400-499 range exist as exit numbers? Because somehow I doubt that.

(Although, I do suppose that I-35/35E through the Dallas area would capture the large majority of them...)

The only one TM's data for Interstates lacks in the 400s is 489.  But it does show an Exit 489 on US 101 in California.

Indeed, I systematically went through this. The 400s are solid.

May seem counterintuitive but you have to keep in mind there are actually a decent number of roads in the US with exit numbers in the 400s, and it only takes one of each to keep the streak up.

In addition to 35/35E, I-20 also hits a lot of numbers in the 400s through the DFW area, and US 101 hits a lot of them through the bay area. I-5 is in the upper 400s in the Manteca/Stockton area. The low-mid 400s get some dense action from I-80 in Lincoln and Omaha, and from I-70 on the KS side of Kansas City.

And if that's not enough for you... I-10 TX, I-90 MT, CA 1, and US 64 NC also all have exits numbers which stretch past 500, and so hit numbers even in the upper 400s. J-75 FL, I-40 TN, I-25 NM, and TX 130 all extend past 450.

[webny99]

I'm going to be a true New Yorker and say I didn't realize how many Interstate highways and US highways with numbered freeway exits run for more than 400 miles within a state. I'm not used to exit numbers exceeding 70 or so - I have to go to either Canada or PA to even find that - so it's not something I think about very often, other than just wishing NY would finally get around to switching to mileage-based. Even so, I-90 and I-87 both have less than 400 miles in the state, so we wouldn't be a big contributor to the 400+ club even with mileage-based exits.

Also, what's up with TX 130's numbering scheme?

[sprjus4]

US-64 in North Carolina has Exits 502, 505, 507, 512, 514, 515, 544, 548, 554, 557, 558, and 562.