De facto X0/X5 Interstates

[Beltway]

I-66 should honestly be a 3di. It's one of the shortest Intersates, and it's shorter than many Interstate spurs (135, anyone?).

I'm too lazy to look it up, but I seem to recall that at least 10 mainline Interstate highways are shorter than I-66 which is 75 miles long.

Connecting I-81 to Washington seems a valid use of a mainline route number.

[sprjus4]

I-66 should honestly be a 3di. It's one of the shortest Intersates, and it's shorter than many Interstate spurs (135, anyone?).

I'm too lazy to look it up, but I seem to recall that at least 10 mainline Interstate highways are shorter than I-66 which is 75 miles long.

Connecting I-81 to Washington seems a valid use of a mainline route number.

I-87 (NC), I-97, I-11, I-14, I-2, I-86 (ID), and I-19 are all shorter than I-66.

In the future, I-87 (NC), I-11, and I-14 are slated to be extended in much longer corridors, and I-19 may be replaced by I-11 in the process. Additionally, while not officially designated, I-2 may eventually be extended to Laredo along the US-83 corridor in the future as well. That would leave I-97 and I-86 being shorter than I-66, all corridors that could reasonably be 3di's.

Reasonably, I could see I-66 being an I-x95, though obviously nowadays it would not be re-numbered.

[DJ Particle]

Reasonably, I could see I-66 being an I-x95, though obviously nowadays it would not be re-numbered.

Wasn't I-66 supposed to eventually extend all the way into Kentucky?

[sprjus4]

Reasonably, I could see I-66 being an I-x95, though obviously nowadays it would not be re-numbered.

Wasn't I-66 supposed to eventually extend all the way into Kentucky?

A later proposal drafted in the 1990s, though never gained any fruition. The most that came were "Future I-66" signs in Kentucky.

Virginia or West Virginia have no plans to construct any piece of the corridor to interstate standards.

[sparker]

Reasonably, I could see I-66 being an I-x95, though obviously nowadays it would not be re-numbered.

Wasn't I-66 supposed to eventually extend all the way into Kentucky?

A later proposal drafted in the 1990s, though never gained any fruition. The most that came were "Future I-66" signs in Kentucky.

Virginia or West Virginia have no plans to construct any piece of the corridor to interstate standards.

The closest thing to a potential I-66 corridor between its present alignment and KY is a combination of ARC corridors "H" and "G" via Charleston, using I-79 northeast of that city.  Seeing as how the progress on "H" has been and likely will continue to be a protracted process due to continuing funding issues (and the terrain doesn't help much either!) just to do an expressway, it would likely be a very long and bumpy slog to get it up to Interstate standards -- and both WV and the Feds will want to take a long break before even entertaining the idea of upgrading H (and G, along US 119, is not even close to I-standards).  But unless KY's proposed I-66 segment along their southern tier is prioritized, the cost of doing so would be unnecessary and, frankly, pointless.  Once completed, Corridor H would have to demonstrate the ability to attract traffic away from competing Interstates in the area before any upgrade plans would be made.   

[bing101]

I-11 is a defacto x5 though. However I-11 was supposed to expand into Reno,  or to Phoenix though at one point

[Hwy 61 Revisited]

I-11 is a defacto x5 though. However I-11 was supposed to expand into Reno,  or to Phoenix though at one point

Check OP.

[sparker]

I-11 is a defacto x5 though. However I-11 was supposed to expand into Reno,  or to Phoenix though at one point

Check OP.

Not really; in fact the I-11 corridor -- especially if it's eventually extended up into Oregon -- would, service-wise, be more or less an analogue of I-81 back East -- a diagonal connector bypassing the major coastal metro areas.  But unlike I-81, which doesn't see many cities with 100K incorporated population, it does hit two major metro areas with over a million residents (PHX and LV, of course), and will come close to another (Reno) with about 300K.  But like so many other Southwest corridors, there's a lot of nothing between those metro areas.   

[bing101]

I-11 is a defacto x5 though. However I-11 was supposed to expand into Reno,  or to Phoenix though at one point

Check OP.

Not really; in fact the I-11 corridor -- especially if it's eventually extended up into Oregon -- would, service-wise, be more or less an analogue of I-81 back East -- a diagonal connector bypassing the major coastal metro areas.  But unlike I-81, which doesn't see many cities with 100K incorporated population, it does hit two major metro areas with over a million residents (PHX and LV, of course), and will come close to another (Reno) with about 300K.  But like so many other Southwest corridors, there's a lot of nothing between those metro areas.

https://en.wikipedia.org/wiki/Interstate_19

Also I-11 was planned to join with I-19 though in a proposal.

[sparker]

I-11 is a defacto x5 though. However I-11 was supposed to expand into Reno,  or to Phoenix though at one point

Check OP.

Not really; in fact the I-11 corridor -- especially if it's eventually extended up into Oregon -- would, service-wise, be more or less an analogue of I-81 back East -- a diagonal connector bypassing the major coastal metro areas.  But unlike I-81, which doesn't see many cities with 100K incorporated population, it does hit two major metro areas with over a million residents (PHX and LV, of course), and will come close to another (Reno) with about 300K.  But like so many other Southwest corridors, there's a lot of nothing between those metro areas.

https://en.wikipedia.org/wiki/Interstate_19

Also I-11 was planned to join with I-19 though in a proposal.

That portion of I-11 paralleling I-10 from Casa Grande southeast to Tucson and then paralleling (or subsuming) I-19 south from there to Nogales serves as the dictionary definition of "gratuitous" or even "superfluous".  Granted, the Tucson area itself probably needs a relief route or two, but that particular I-11 segment doesn't even fit the bill, being a long-range western bypass of the city.  IMO, the farthest south I-11 should get is Casa Grande -- and even the section from there northwest to I-10 at Buckeye, while an effective Phoenix bypass for both I-10 and I-11 traffic, was initiated primarily to enhance development south of Phoenix.  All that is the result of local developers and interests "tacking on" their ambitions to a Phoenix-Vegas intercity corridor concept, to the detriment of attention being paid to actually building the main "stem" northwest of Phoenix.   

[Hwy 61 Revisited]

I-11 is a defacto x5 though. However I-11 was supposed to expand into Reno,  or to Phoenix though at one point

Check OP.

Not really; in fact the I-11 corridor -- especially if it's eventually extended up into Oregon -- would, service-wise, be more or less an analogue of I-81 back East -- a diagonal connector bypassing the major coastal metro areas.  But unlike I-81, which doesn't see many cities with 100K incorporated population, it does hit two major metro areas with over a million residents (PHX and LV, of course), and will come close to another (Reno) with about 300K.  But like so many other Southwest corridors, there's a lot of nothing between those metro areas.

https://en.wikipedia.org/wiki/Interstate_19

Also I-11 was planned to join with I-19 though in a proposal.

That portion of I-11 paralleling I-10 from Casa Grande southeast to Tucson and then paralleling (or subsuming) I-19 south from there to Nogales serves as the dictionary definition of "gratuitous" or even "superfluous".  Granted, the Tucson area itself probably needs a relief route or two, but that particular I-11 segment doesn't even fit the bill, being a long-range western bypass of the city.  IMO, the farthest south I-11 should get is Casa Grande -- and even the section from there northwest to I-10 at Buckeye, while an effective Phoenix bypass for both I-10 and I-11 traffic, was initiated primarily to enhance development south of Phoenix.  All that is the result of local developers and interests "tacking on" their ambitions to a Phoenix-Vegas intercity corridor concept, to the detriment of attention being paid to actually building the main "stem" northwest of Phoenix.

I heard that 11 was supposed to replace 19

[sparker]

I heard that 11 was supposed to replace 19

Several options for I-11 from Casa Grande down to Nogales have been proposed; one of them bypasses Tucson to the west and joins I-19 a few miles south of the city, and utilizes the I-19 alignment the rest of the way to Mexico (the others simply parallel it several miles to the west).  But nothing is written in stone at this time; all prospects remain simply speculative. 

[OCGuy81]

X4 seems a lot more used than X2.

14, 24, 44, 64, 74, 84, 94

X2s

22 (fairly recent), 72, 82 (which should be a N-S designation, IMO)

[Roadgeekteen]

Reasonably, I could see I-66 being an I-x95, though obviously nowadays it would not be re-numbered.

Wasn't I-66 supposed to eventually extend all the way into Kentucky?

I even saw an I-66 plan extending it to California.

[Hwy 61 Revisited]

Is there a hierarchy for route numbering? Like, some numbers are higher than others?

Reasonably, I could see I-66 being an I-x95, though obviously nowadays it would not be re-numbered.

Wasn't I-66 supposed to eventually extend all the way into Kentucky?

I even saw an I-66 plan extending it to California.

Lemme guess, FritzOwl's.

[frankenroad]

82 (which should be a N-S designation, IMO)

I concur - in my fictional renumbering of the interstate system, it's I-13.

[Roadgeekteen]

Is there a hierarchy for route numbering? Like, some numbers are higher than others?

Reasonably, I could see I-66 being an I-x95, though obviously nowadays it would not be re-numbered.

Wasn't I-66 supposed to eventually extend all the way into Kentucky?

I even saw an I-66 plan extending it to California.

Lemme guess, FritzOwl's.

No, it's mentioned on the Wikipedia page for I-66.

[sprjus4]

Is there a hierarchy for route numbering? Like, some numbers are higher than others?

Reasonably, I could see I-66 being an I-x95, though obviously nowadays it would not be re-numbered.

Wasn't I-66 supposed to eventually extend all the way into Kentucky?

I even saw an I-66 plan extending it to California.

Lemme guess, FritzOwl's.

It was an actual proposal in the 1990s, though never went anywhere.

[DJ Particle]

Is there a hierarchy for route numbering? Like, some numbers are higher than others?

Reasonably, I could see I-66 being an I-x95, though obviously nowadays it would not be re-numbered.

Wasn't I-66 supposed to eventually extend all the way into Kentucky?

I even saw an I-66 plan extending it to California.

Lemme guess, FritzOwl's.

It was an actual proposal in the 1990s, though never went anywhere.

I think the proposal was meant to bring back the whole "mother road"/"66" nostalgia.

[sparker]

Is there a hierarchy for route numbering? Like, some numbers are higher than others?

Reasonably, I could see I-66 being an I-x95, though obviously nowadays it would not be re-numbered.

Wasn't I-66 supposed to eventually extend all the way into Kentucky?

I even saw an I-66 plan extending it to California.

Lemme guess, FritzOwl's.

It was an actual proposal in the 1990s, though never went anywhere.

I think the proposal was meant to bring back the whole "mother road"/"66" nostalgia.

The numbering choice was certainly part of that corridor's selling points.  The proposal, which dates from about 1987, was called the "Transamerica" corridor (no connection to the S.F. pyramid skyscraper of the same name!).  Similar to the I-69 corridor, it was cobbled together from separate proposals in Virginia, Kentucky, Kansas, and California.  The California section was promoted by Fresno interests in order to put them on a major cross-country E-W corridor.  Of course it included a major Sierra crossing -- envisioned as a series of tunnels more or less along the Sequoia/Kings Canyon national park common border, then shunting down US 395 to CA 136, then on across Death Valley along CA 190, coming into Nevada at Pahrump (where travelers could avail themselves of carnal pleasure for a nominal fee!), on to Las Vegas, then MPXing with I-15 up to St. George.  It would zig-zag along the AZ/UT border, passing near 4 Corners, and then follow US 160 to Walsenburg, CO.  From there it would continue east along CO 10 before following us 50 and the entirety of US 400 via Wichita (where its primary midwest backers hailed from), then across US 60 through MO into KY, where it traced the later I-66 track across the southern tier of parkways and into WV.  It used the then-nascent Coalfields parkway to Beckley, then up US 19 across the New River high bridge before segueing onto ARC Corridor "H" all the way to the real I-66 -- which was extended across the Chesapeake Bay before ending up at either Dover or Ocean City, MD (that was never "finalized").  Of course, once the concept was published in the summer of '87, environmental opposition to pretty much everything west of Kansas was lodged.  When the ISTEA authorizing legislation was passed in 1991, much of the eastern half of the corridor was enshrined as HPC #3 -- but with a southern shift in VA to a US 460-based corridor across the state.  West of Wichita, the corridor definition was deliberately vague -- it could be interpreted as going to San Diego, L.A., Bakersfield -- you name it -- pretty much everywhere except Fresno! 

In retrospect, the corridor was like the proverbial "camel's origin as a horse designed by a committee".  Pretty much every aspect of the western Transamerica section passed through protected and/or scenic areas such as the CA South Sierra national parks, Death Valley, Monument Valley, Durango, etc.  Except for a couple of Central CA representatives, there was zero Congressional support for the corridor west of Kansas.  Once ISTEA was in the books, the original Wichita backers tried (to no avail) to get the HPC #3 corridor re-specified along US 54 down to I-40 in NM, and then out I-40 all the way to its CA terminus so they would have access from both directions.  They had to wait for 2005's SAFETEA-LU before securing that particular place in the HPC litany with HPC #51 along US 54 from Wichita to El Paso.

Like with the I-69 corridor, the Transamerica concept strung together priorities from various regions along the route -- but their penchant for picking the more environmentally sensitive alignments out West doomed that corridor segment from the beginning.  They essentially wanted to put a corridor in locations that no rational planner would consider on their most cynical day  -- there's a reason why there isn't a freeway through Kings Canyon and Death Valley, skirting Zion N.P., bisecting Monument Valley, and crossing the southern Colorado Rockies.  Calling it I-66 was the least troublesome aspect of the proposal.     

[Avalanchez71]

X4 seems a lot more used than X2.

14, 24, 44, 64, 74, 84, 94

X2s

22 (fairly recent), 72, 82 (which should be a N-S designation, IMO)

What about 4 itselft?

[hotdogPi]

It makes sense that more X4s and X6s get used than X2s and X8s. 4 and 6 are routes that are halfway between major X0 Interstates, while 2 and 8 are closer to an X0 and wouldn't be needed as much.

Even
Major: 10, 20, 30, 40, 70, 80, 90 (7)
Adjacent: 2, 8, 12, 22, 42, 68, 72, 78, 82, 88, 88 (11)
Away: 4, 14, 16, 24, 26, 44, 64, 66, 74, 76, 76, 84, 84, 86, 86, 94, 96 (16, 17 if you count 74 twice)

Odd
Major: 5, 15, 25, 35, 45, 55, 65, 75, 85, 95 (10)
Adjacent: 17, 27, 37, 43, 57, 73, 77, 83, 87, 87, 93, 97 (12)
Away: 11, 19, 29, 39, 41, 49, 59, 69, 71, 79, 81, 89, 91, 99 (14)

[I-55]

X4 seems a lot more used than X2.

14, 24, 44, 64, 74, 84, 94

X2s

22 (fairly recent), 72, 82 (which should be a N-S designation, IMO)

What about 4 itself?

Or I-2?

I think the reason they picked x4s is because it gives the option to have a route number available to the north and south, whereas if they picked an x2 there wouldn't be the ability to put anything new between it and the x0. The four x2s in existence do not create problems: I-2 is about as far south as you can go, I can't see anything EW between I-22 and I-20, I-72 and I-82 are the last available even numbers in the 80s and 90s (though I-82 is off the grid and its orientation is debatable).

Though based off that logic you could argue for x6s instead of x4s (if nothing between the x0s had been used yet. If there was already an x2 then the x6 would be more appropriate, etc.)

[Big John]

I-82 are the last available even numbers in the 80s and 90s (though I-82 is off the grid and its orientation is debatable).

I-92 and I-98 are available.

[US 89]

(though I-82 is off the grid and its orientation is debatable)

Orientation issues aside, 82 is numbered as such because 84 used to be 80N.