Longest Interstate You Haven't Been On

[Ian]

I-75 for me. I've crossed it at two separate locations (Dayton and Toledo), but I've not driven any of its mileage.

[Duke87]

I-11 and I-22 are the only 2dis in the continental US I have never been on any segment of. So I-22 is the answer.

As for US highways, there are a total of 25 of those I have not been on (excluding directional suffixed splits). US 550, at 298.36 miles (per TravelMapping data), is the longest.

[cjk374]

I-35 I briefly used I-35W during my last Twin Cities trip

So mine would be I-10

I wouldn't count suffixed routes as part of the main route for this discussion whether it is mileposted or legislatively defined or not. Just me being me.

If you drive I-35E or W, seeing their reassurance assemblies, but never have driven I-35 and seen its reassurance assemblies, then (my opinion) you haven't driven any of I-35.

[Beltway]

I wouldn't count suffixed routes as part of the main route for this discussion whether it is mileposted or legislatively defined or not. Just me being me.
If you drive I-35E or W, seeing their reassurance assemblies, but never have driven I-35 and seen its reassurance assemblies, then (my opinion) you haven't driven any of I-35.

But what if you drove on I-35E in Dallas?  Does I-35 even conceptually not exist in the DFW area?

[ET21]

I wouldn't count suffixed routes as part of the main route for this discussion whether it is mileposted or legislatively defined or not. Just me being me.
If you drive I-35E or W, seeing their reassurance assemblies, but never have driven I-35 and seen its reassurance assemblies, then (my opinion) you haven't driven any of I-35.

But what if you drove on I-35E in Dallas?  Does I-35 even conceptually not exist in the DFW area?

Depends on if that is officially labeled legislatively and mileposts as the main I-35 routing like what froggie said about I-35E in St. Paul.

[Beltway]

But what if you drove on I-35E in Dallas?  Does I-35 even conceptually not exist in the DFW area?

Depends on if that is officially labeled legislatively and mileposts as the main I-35 routing like what froggie said about I-35E in St. Paul.

This what Wikipedia says on article Interstate 35E (Texas) --

Interstate 35E (I-35E), an Interstate Highway, is the eastern half of I-35 where it splits to serve the Dallas/Fort Worth metropolitan area. I-35 splits into two branch routes, I-35W and I-35E at Hillsboro.  I-35E travels northward for 97 miles (156 km), maintaining I-35's sequence of exit numbers.

[lordsutch]

In my case, I'm pretty sure it's I-29.

[paulthemapguy]

^ Technically, I-35W in the Twin Cities is separate from I-35.  I-35 "follows" I-35E through St. Paul both legislatively and via mileposts.

So then my plan to change I-35W to I-33 would be easier to implement because I hate letter suffixes 

[TheCatalyst31]

I-20 for me.

I-35 I briefly used I-35W during my last Twin Cities trip

So mine would be I-10

I wouldn't count suffixed routes as part of the main route for this discussion whether it is mileposted or legislatively defined or not. Just me being me.

If you drive I-35E or W, seeing their reassurance assemblies, but never have driven I-35 and seen its reassurance assemblies, then (my opinion) you haven't driven any of I-35.

This discussion is moot anyway, since I-10 is longer than I-35.

[PHLBOS]

I-10

[bzakharin]

I've never driven on I-90. I may have been on it as a passenger during either a trip to Niagara Falls or Rochester or both, or neither. Again possibly while in the Cleveland area. Barring that, I-40. The longest N-S is I-75

[TheHighwayMan3561]

I consider 35E to be 35 in both cases, so I'd count driving on 35E but not either 35W as 35.

[Beltway]

I consider 35E to be 35 in both cases, so I’d count driving on 35E but not either 35W as 35.

I drove thru the DFW area in 1972 east-west on the turnpike and what was then I-20 thru downtown Dallas (today's I-30).  Looks like I overlapped a mile of I-35E, so it looks like I have driven a part of I-35 after all.

[Buck87]

I-45

[catch22]

I-20 for me.

I've been on at least some part of every I-x0 and I-x5 except this one and I-45.

[michravera]

I was curious what mine was. Looked it up, and found out it was I-25. Odd, considering I've been through all three states I-25 is in.

What's yours?

I believe that I have been on (or at crossed at right angles) all of the interstates that are over about 1000 km. Some of this was before they were designated as interstates or fully constructed. Most of my coast-to-coast driving travel occurred in 1975. I could be missing I-20 or I-30, but I believe that I crossed it at right angles in 2015.

[Duke87]

I wouldn't count suffixed routes as part of the main route for this discussion whether it is mileposted or legislatively defined or not. Just me being me.
If you drive I-35E or W, seeing their reassurance assemblies, but never have driven I-35 and seen its reassurance assemblies, then (my opinion) you haven't driven any of I-35.

But what if you drove on I-35E in Dallas?  Does I-35 even conceptually not exist in the DFW area?

To take this a step further: if you count directional splits as separate routes, is the unsuffixed version all one route or are there two routes with the same number on either side of the directional split?

This makes no difference in my case for interstates but it does for US routes - US 45 south of where it splits into US 45W and US 45E is longer than US 550, and I have never been on any of it down there. So if we consider this to be a separate "southern US 45" (much as there are two separate routes numbered I-76, 84, 86, 87, and 88), that would then take on the title of longest US route I have never been on.


This is why I deliberately specified "excluding directional splits". For the purpose of this exercise it is more straightforward if US 45, 45W, and 45E all count as "US 45", and I would say that is fair in general.

The one exception I might make is US 9W... since there is no corresponding 9E. US 9 has a single distinct path and US 9W has a different path, thus making it a distinct US route of its own.
(trivia: there was a US 9W/9E pair on either side of the Hudson from 1926 to 1930, after that 9E became plain 9)

[mrcmc888]

For me it's I-20, despite passing it in Atlanta frequently I've never been on any of it.

[froggie]

FWIW, FHWA considers the I-35E branches to be part of I-35.

[webny99]

I haven't been on I-5, I-15, or I-25. I was surprised to learn, however, that I-20 is actually longer than all of the aforementioned I-X5's, so I guess it takes the cake in my case.
Other than that, I have been on every I-X0 except I-30, which is fairly short and therefore not really a contender. I have never been on I-65 or I-85, either, but those are considerably shorter than their counterparts out west.

Discussion of I-35/I-35E/I-35W seems to be a theme here... so I might as well add that, yes, I have been on I-35 (no suffix) and both I-35W and I-35E in the Twin Cities area - multiple times. 

[TheHighwayMan3561]

In 45's case, it appears W continues the mileposts from mainline 45 while E is a separate route.

Everybody has their own rules, which is fine, but it's clear that one branch is intended to be the spiritual successor while the other one is otherwise entirely a separate route. When I clinched I-35, I made it a point to take 35E through DFW, and would not have considered 35 clinched if I had taken 35W instead.

[hbelkins]

In 45's case, it appears W continues the mileposts from mainline 45 while E is a separate route.

Tennessee is special, because the US routes have hidden state routes, and the mileposts are for the state routes. Also, in Tennessee, mileposts on non-interstates reset at county lines.

For me, I consider them discontinuous routes if they have a suffixed pair in the middle, and those suffixed pairs are two separate routes. Say you're driving US 31 south out of Michigan and Indiana, and you get to their split in Louisville. (Which is a bit complicated, because there are a bunch of one-way streets carrying the two split routes.) It does not matter if you take 31E, 31-Dub by the infamous little green shrub, or get on I-65, to get to Nashville. If you pick up US 31 at the point where the routes rejoin and follow 31 all the way to its terminus, it has been clinched or traveled on.

If you have traveled only on US 31E or US 31W, you have not traveled on US 31. (And I realize we're talking about Interstates in this thread, and there's a specific mention made of the I-35 situation, but someone mentioned the US routes.)

[CNGL-Leudimin]

About the I-35 splits, I consider I-35 not to exist between Hillsboro and Denton TX and between Burnsville and Lino Lakes MN. So I consider three separate I-35s exist.

[CtrlAltDel]

In 45's case, it appears W continues the mileposts from mainline 45 while E is a separate route.

Everybody has their own rules, which is fine, but it's clear that one branch is intended to be the spiritual successor while the other one is otherwise entirely a separate route. When I clinched I-35, I made it a point to take 35E through DFW, and would not have considered 35 clinched if I had taken 35W instead.

About the I-35 splits, I consider I-35 not to exist between Hillsboro and Denton TX and between Burnsville and Lino Lakes MN. So I consider three separate I-35s exist.

Not to give yet another opinion, but I consider only one I-35 to exist, and it comprises both the W and E branches. So, I wouldn't consider I-35 to be clinched unless I had driven both the W and the E in both Texas and Minnesota.

[adventurernumber1]

Not to give yet another opinion, but I consider only one I-35 to exist, and it comprises both the W and E branches. So, I wouldn't consider I-35 to be clinched unless I had driven both the W and the E in both Texas and Minnesota.

That is probably how my views lie on the suffixed I-35 thing. In criteria for me personally clinching I-35, I would either require that I took at least one suffix and clinch it (such as driving all of both I-35Ws or all of both I-35Es), or all of both. For the clinching part, I would probably do the former.