I've had a burning question in regards to a portion of US 1, more particularly its routing between Jacksonville, FL and Philadelphia, PA. North of Jacksonville, US 1 beelines northwest into Georgia where it follows an inland trek. It remains inland through South Carolina, North Carolina and Virginia where it starts to make it's way back toward the eastern coastline. On the other hand, routes US 17 and US 13 (which clearly should be west of US 1) follow the eastern coastline more closely. My question is, why doe this occur? Was there some sort of purpose for US 1 to be more inland in these states, with those higher numbered US highways being east, or was there some sort of mishap in the initial designation, mistakenly switching the routing of US 1 with that of US 17 and 13?
from Wikipedia:
When the road system was laid out in the 1920s, U.S. 1 was mostly assigned to the existing Atlantic Highway, which followed the Fall Line between the Piedmont and the Atlantic Coastal Plain north of Augusta.[2] At the time, the highways farther east were of lower quality and did not serve the major population centers. [3]
I knew I should have consulted you first as I figured you'd be the first to answer my post...hehe
Thanks for directing to the answer (even it was via Wikipedia). I sort of knew in the back of my mind that there was some sort of significance to the routing of US 1 but never thought of where exactly to look, which is why I posted here.
Maybe we can get some other questions/answers/thoughts about the numbering of the US Highway system posted here for future enjoyment.
Hey, Wikipedia's road coverage is pretty good. We have a dedicated crew of roadgeeks that keeps the articles maintained. The only problem is that we have more articles than we do roadgeeks so some states aren't covered as well. The Northeast, California, Washington State, Michigan, Ohio, Utah, and Oklahoma are all pretty well covered. The rest of the states get help whenever someone in a nearby state has the spare time and interest to edit that state. (I work on OK but will hop into KS, MO, and AR every so often.) We can always use more help though!
Off Topic here, but the Wikipedia concept was brought up:
I've seen outlandish things written on Wikipedia, like "Interstate 70 is planned to extend westward to the San Franciso bay area to replace Interstate 238". Andy and I read that in 2005 and laughed like crazy. Some of the wikipedia people also steal our information and claim its their own, i.e. Andy's photo of I-680/780 on http://en.wikipedia.org/wiki/Benicia-Martinez_Bridge (http://en.wikipedia.org/wiki/Benicia-Martinez_Bridge) :ded:
How do you go about complaining about this theft to have it removed, because no, that photo is not free for use by anyone? If you want a pic of that sign bridge for commercial use, go out there and photograph it yourself, don't take the work of others and claim anyone can use it! Perhaps one of our members here can PM me or Andy and tell us what we could do about that.
You could go about complaining by adding a tag onto the image saying that it violates a copyright (I know it can be done, but not how to do it--I'm not a wikipedia expert), or post on the user who uploaded it's talk page: http://en.wikipedia.org/wiki/User_talk:Ryanloney. (http://en.wikipedia.org/wiki/User_talk:Ryanloney.)
Oh and if you look on the image's page, the user even claims he's the copyright holder! :wow:
Yes, Andy has already tried and looked into it, to no avail.
That part about him being the copyright holder infuriates us. Like I said before, if you want the image, you put the effort into driving and taking the photo yourself. We don't mind photos being used for road sites, but at least acknowledge the fact that we took the photo and from where you got it.
I take my own roadgeek photos for Wikipedia :) :
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fen%2Fthumb%2F4%2F44%2FNY_31B_Reference_Marker.jpeg%2F450px-NY_31B_Reference_Marker.jpeg&hash=7af4be65f159fe37a7f444c4463aa6eda67ac94a) (http://en.wikipedia.org/wiki/File:NY_31B_Reference_Marker.jpeg)
Marked that photo for deletion, it should be gone in a couple hours. If you could give me the exact url of the pic on your site, that would be great.
The theft of photos is an annoying. I uploaded a number of old racing photos I took in the late 70's and early 80's to flickr. I thought a couple of people might find them interesting. I went to the local track one night and bought a poster that they were selling. Lo and behold, 4 of the images on the racing collage were lifted from my flickr pages. Very annoying. I should have at least gotten a free poster!
I have quite a few images that are used in wikipedia, but someone always asked.
Quote from: John on January 26, 2009, 04:02:44 PM
Marked that photo for deletion, it should be gone in a couple hours. If you could give me the exact url of the pic on your site, that would be great.
http://www.westcoastroads.com/california/images701/i-780_eb_exit_007a_02.jpg (http://www.westcoastroads.com/california/images701/i-780_eb_exit_007a_02.jpg)
Thanks!!
Quote from: Scott5114 on January 26, 2009, 04:54:38 AM
Hey, Wikipedia's road coverage is pretty good. We have a dedicated crew of roadgeeks that keeps the articles maintained. The only problem is that we have more articles than we do roadgeeks so some states aren't covered as well. The Northeast, California, Washington State, Michigan, Ohio, Utah, and Oklahoma are all pretty well covered. The rest of the states get help whenever someone in a nearby state has the spare time and interest to edit that state. (I work on OK but will hop into KS, MO, and AR every so often.) We can always use more help though!
I just don't have a lot of time to work on Arkansas... or patience with Wikipedia's odd formatting. I dabble when I have time.
Quote from: Scott5114 on January 26, 2009, 04:54:38 AM
Hey, Wikipedia's road coverage is pretty good. We have a dedicated crew of roadgeeks that keeps the articles maintained. The only problem is that we have more articles than we do roadgeeks so some states aren't covered as well. The Northeast, California, Washington State, Michigan, Ohio, Utah, and Oklahoma are all pretty well covered. The rest of the states get help whenever someone in a nearby state has the spare time and interest to edit that state. (I work on OK but will hop into KS, MO, and AR every so often.) We can always use more help though!
The roadgeeks maintaining Wikipedia's road articles are pretty vigilant, making sure vandalism and blatant falsehoods are removed in a timely manner. Personally, I am working on Nevada highways and have all such articles on my watchlist. One thing I noticed is that many of the Nevada articles were started by basically taking information right out of the AARoads Nevada route logs--I've been removing/expanding that with other sources as my time permits.
Anyway, you might take a look at some of the Featured, A-Class, or Good Articles of the US Roads Wikiproject to see some of the more high-quality articles produced by the community.
if only the shield images weren't so terrible at times!
Quote from: agentsteel53 on January 27, 2009, 01:25:48 AM
if only the shield images weren't so terrible at times!
We try and follow the standard to the letter as far as possible. All our Interstate shields are generally made to the SHS 2003 standard for instance. Likewise our color palette is drawn straight from the Pantone color standards that are on the MUTCD webpages. Of course, signs you see in the field might not meet the standard–many DOTs tend to take liberties with the standards (often the blue is a lot brighter than standard). We try to mitigate this by following the state DOT's standard when it's available, but of course many states don't do that.
The quality might slip for historic shields since the exact standards and fonts (especially weird DOT-unique fonts) are typically impossible to find. Many of us are unfamiliar with what historic shields were used at what times. If you could highlight some of the stuff you have problems with we'll work on it!
By the way, I am an administrator on Wikipedia. If you have any problems regarding people thefting your images or any other concern (especially if it relates to the road projects) feel free to send me any concerns either through PM here, my Wikipedia talk page (http://en.wikipedia.org/wiki/User:Scott5114), or by email. Copyright infringement is a big deal at Wikipedia. Also, the U.S. Roads project is made up of roadgeeks just like this forum is and we want to work well with the roadgeek community!
Quote from: roadfro on January 27, 2009, 01:23:26 AM
The roadgeeks maintaining Wikipedia's road articles are pretty vigilant, making sure vandalism and blatant falsehoods are removed in a timely manner. Personally, I am working on Nevada highways and have all such articles on my watchlist. One thing I noticed is that many of the Nevada articles were started by basically taking information right out of the AARoads Nevada route logs--I've been removing/expanding that with other sources as my time permits.
I've been trying to get Nevada somewhere off and on, but man is it a mess. Besides the US/I routes, 28, and 88, I can't think of a single article above start-class.
Quote from: Scott5114 on January 27, 2009, 02:50:50 AM
The quality might slip for historic shields since the exact standards and fonts (especially weird DOT-unique fonts) are typically impossible to find. Many of us are unfamiliar with what historic shields were used at what times. If you could highlight some of the stuff you have problems with we'll work on it!
those are the ones I'm talking about. I remember the "US Route Shield" article having a terrible Arizona US 66 with all the wrong fonts!
Quote from: agentsteel53 on January 27, 2009, 04:47:30 PM
those are the ones I'm talking about. I remember the "US Route Shield" article having a terrible Arizona US 66 with all the wrong fonts!
It appears to be gone now!
I hate to burst bubbles here, but can we get back on track...? Maybe all these Wikipedia posts can be started in their own thread??
Reviving this old thread because of a thought I just had:
Obviously, the grids were not designed to be as strict as those of the later Interstate system, which leads to an interesting point:
This is more noticeable for the x1 routes than the x0 routes (as the x0 routes tended to be very strictly transcontinental - even receiving superflous extensions to the west in the case of US 70 and US 50 in order to meet this claim), but what determinations made a route "major" (x1) as opposed to minor (the other odd last digits)?
Sometimes this is very obvious - US 1 - but then I find it rather intriguing that US 11, ostensibly a "major" route in that system, was supplanted for through traffic by the "non-major" I-59 and I-81; I-77 became the parallel/replacement Interstate for US 21.
Other corridors seemed to have become more important by the 1950s, i.e. I-25 paralleling/supplanting US 85.
Quote from: TheStranger on July 23, 2010, 06:27:53 PM
Other corridors seemed to have become more important by the 1950s, i.e. I-25 paralleling/supplanting US 85.
was that corridor in general important in the 1920s? i.e. were Denver and Albuquerque of any significance? Bear in mind that between US-81 and US-91 is a very long gap, and generally not a heavily populated one. 81 or 83 is where the great plains population thins out, and 91 is straight through the mountains once it leaves Los Angeles.
Quote from: Scott5114 on January 27, 2009, 04:53:41 PM
Quote from: agentsteel53 on January 27, 2009, 04:47:30 PM
those are the ones I'm talking about. I remember the "US Route Shield" article having a terrible Arizona US 66 with all the wrong fonts!
It appears to be gone now!
There's this one for 666:
http://road-less-taken.blogspot.com/2009/04/caveat-emptor.html
Quote from: agentsteel53 on July 23, 2010, 06:42:39 PM
Quote from: TheStranger on July 23, 2010, 06:27:53 PM
Other corridors seemed to have become more important by the 1950s, i.e. I-25 paralleling/supplanting US 85.
was that corridor in general important in the 1920s? i.e. were Denver and Albuquerque of any significance? Bear in mind that between US-81 and US-91 is a very long gap, and generally not a heavily populated one. 81 or 83 is where the great plains population thins out, and 91 is straight through the mountains once it leaves Los Angeles.
Looking at the routing of 81, the major cities on it (1920 populations listed in parentheses) are San Antonio (161K), Austin (34K), Fort Worth (106K), Wichita (72K)...then Fargo (21K).
Seems like US 81 gained its x1 number by being rather important in Texas more than anywhere else...kinda like how US 101 seems to have received its number basically for the San Diego to Santa Rosa stretch, even though the 99 corridor was border-to-border and also hit up the two most important Pacific Northwest cities, as well as the capital of California.
For comparison, along US 85, the populations were 77K for El Paso, 15K for Albuquerque, 43K for Pueblo, 30K for Colorado Springs, 256K for Denver, 10K for Greeley, and 13K for Cheyenne.
Quote from: US71 on July 23, 2010, 07:15:59 PM
There's this one for 666:
http://road-less-taken.blogspot.com/2009/04/caveat-emptor.html
that one's a bit better, but the shield needs an outer border.
I never knew or thought of the x1 routes being more primary than the x5 routes, but looking at the grid, it does make sense.
I believe the US highway system used x1 and x0 as the primary transcontinentals with x5 being a secondary transcontinental.
Quote from: deanej on July 25, 2010, 02:01:26 PM
I believe the US highway system used x1 and x0 as the primary transcontinentals with x5 being a secondary transcontinental.
US 15, 25, 45, 65, 75, 85, and 95 fit that...but US 5, 35, and decommissioned 55 don't - and 95 was originally created as a very short route in Idaho.
Well, US5 just happened to be at a very thin part of the country.
Quote from: yakra on July 25, 2010, 10:21:11 PM
Well, US5 just happened to be at a very thin part of the country.
I'm just imagining how much difficulty Chile would have in developing a grid-based system. How do they manage their numbering?
if i recall correctly, x1 and x5 were designated as the primary N-S routes simply because the country was wider than using x5 or x1 routes alone....you got pretty good E-W coverage with the x0 routes....of course US 35 was a late-comer to the party, as were the US 95 extensions...
Interestingly enough, though, both US 10 and US 90 were never designed to be full transcontinental highways. The same goes with US 20... It used to end at the east end of Yellowstone until the 1940s, when it was extended west to Newport, OR. This is why Oregon violates the grid system. (US 26 should be south of US 20 and north of US 30, but it's not.)
It also comes down to the fact that many US highways have been extended, truncated or realigned since 1926. This is why US 41, for example, runs in a very diagonal pattern, why US 6 is somehow way down in LA and why route numbers such as 400 and 412 exist.
Quote from: Quillz on August 30, 2010, 10:13:33 PMwhy route numbers such as 400 and 412 exist.
that is just capriciousness in numbering - nothing to do with extending old routes. Those two were formed out of whole cloth in the early 80s.
Quote from: agentsteel53 on August 30, 2010, 10:20:49 PM
Quote from: Quillz on August 30, 2010, 10:13:33 PMwhy route numbers such as 400 and 412 exist.
that is just capriciousness in numbering - nothing to do with extending old routes. Those two were formed out of whole cloth in the early 80s.
Oh, I know, I was just saying that the US Route system has seen a lot of changes over the years, so there are many numbers that are located in places that don't make much sense.
For me, US 6 being anywhere close to California has always kind of annoyed me. And then there's the fact that despite the number implying it's *NOT* a transcontinental highway, it was the longest road in America until 1964, at which point US 20 became the longest.
Actually, I think the US route system had one huge advantage over the Interstate system: flexibility.
Other than the x1 and x0 routes (and to some extent x5), anything else could be as diagonal as necessary. Often times this was taken to excessive extremes (52, 62, 68, 33, 35) but usually this allowed for 2 digit routes to be placed wherever needed, as opposed to the issue the Interstates have of running out of 2 digit numbers due to the grid being too closely laid out.
best comparison? US 11, as opposed to I-81 and I-59 being two entirely seperate interstates on different planes of that grid, following that one corridor.
Having said that, does that explain 44 and 46 being WAY out of the grid? X-( And how about 59/96!?
I think it's too flexible, though... There was a reason for 3di, to fill in the gaps and run diagonal if necessary. There are many examples of 3di US Routes that don't get anywhere near their parent, like US-395. Those are the routes that can run diagonal or connect to places the parent won't touch.
Quote from: Quillz on August 31, 2010, 12:57:29 AM
I think it's too flexible, though... There was a reason for 3di, to fill in the gaps and run diagonal if necessary. There are many examples of 3di US Routes that don't get anywhere near their parent, like US-395. Those are the routes that can run diagonal or connect to places the parent won't touch.
395 was once upon a time a minor branch of 195 before it was extended extremely southward. this was even before 95 left the confines of Idaho.
Quote from: Quillz on August 31, 2010, 12:57:29 AM
I think it's too flexible, though... There was a reason for 3di, to fill in the gaps and run diagonal if necessary. There are many examples of 3di US Routes that don't get anywhere near their parent, like US-395. Those are the routes that can run diagonal or connect to places the parent won't touch.
As Jake noted, 395 was originally a very minor route once upon a time. Having said that, a lot of the awkward 2-digit routes don't really seem to have a "parent" and function as their own extended corridors, particularly something as out-of-grid as 59.
Quote from: Quillz on August 30, 2010, 10:13:33 PM
Interestingly enough, though, both US 10 and US 90 were never designed to be full transcontinental highways. The same goes with US 20... It used to end at the east end of Yellowstone until the 1940s, when it was extended west to Newport, OR. This is why Oregon violates the grid system. (US 26 should be south of US 20 and north of US 30, but it's not.)
Quibble: US 26 in Oregon is exactly where it should be: Between US 20 and 30. It's US 20 and 30 that are in the wrong order; swap them and everything's fine.
But there's little to no point to swapping them, as doing so wouldn't be doing the Public At Large any service (they don't care about the route order), the cost to swap the signs wouldn't be justified, the Historic US 30 shields on OR 100 would make no sense at all, and given that AASHTO would have to sign off on this, I really wouldn't want to give them ammo to force the decommissioning of the US 30 corridor in Oregon on the grounds that it largely duplexes with I-84 and forcing OR 2 to be signed from Astoria to Portland with Bus I-84 taking US 30's place east of Portland. *shudders*
Quote from: Bickendan on September 04, 2010, 01:09:47 AM
Quibble: US 26 in Oregon is exactly where it should be: Between US 20 and 30. It's US 20 and 30 that are in the wrong order; swap them and everything's fine.
But there's little to no point to swapping them, as doing so wouldn't be doing the Public At Large any service (they don't care about the route order), the cost to swap the signs wouldn't be justified, the Historic US 30 shields on OR 100 would make no sense at all, and given that AASHTO would have to sign off on this, I really wouldn't want to give them ammo to force the decommissioning of the US 30 corridor in Oregon on the grounds that it largely duplexes with I-84 and forcing OR 2 to be signed from Astoria to Portland with Bus I-84 taking US 30's place east of Portland. *shudders*
I doubt very much in that scenario that they'd call it OR 2. My guess is they'd call it OR 30, like they did when they decommed US 99 and US 126 years ago. If not, then I'd guess they'd go with OR 92, making the Route Number match the Highway Number.
I know this has nothing to do with the current topic at hand, but do US Route 3di leading digits mean anything?
Like with the Interstate system, when the leading digit is even, it's supposed to connect an Interstate to an Interstate or act as a loop/bypass of its parent route. When the leading digit is odd, it's a spur that is supposed to only connect to an Interstate at one end.
Do the US Route 3di work the same way?
Quote from: Quillz on September 04, 2010, 01:24:18 AM
I know this has nothing to do with the current topic at hand, but do US Route 3di leading digits mean anything?
Like with the Interstate system, when the leading digit is even, it's supposed to connect an Interstate to an Interstate or act as a loop/bypass of its parent route. When the leading digit is odd, it's a spur that is supposed to only connect to an Interstate at one end.
Do the US Route 3di work the same way?
They were originally assigned in the order that the spur route from that parent was created. There also seems to be a general pattern of north-to-south for odd 2dus and east-to-west for even 2dus. Of course, as routes were decommissioned and others added, many available numbers got recycled to new routes.
Quote from: xonhulu on September 04, 2010, 01:30:14 AM
Quote from: Quillz on September 04, 2010, 01:24:18 AM
I know this has nothing to do with the current topic at hand, but do US Route 3di leading digits mean anything?
Like with the Interstate system, when the leading digit is even, it's supposed to connect an Interstate to an Interstate or act as a loop/bypass of its parent route. When the leading digit is odd, it's a spur that is supposed to only connect to an Interstate at one end.
Do the US Route 3di work the same way?
They were originally assigned in the order that the spur route from that parent was created. There also seems to be a general pattern of north-to-south for odd 2dus and east-to-west for even 2dus. Of course, as routes were decommissioned and others added, many available numbers got recycled to new routes.
When you say "the order from that parent," do you mean sequential order, like the first spur built was 1xx, or do you mean in order geographically, from north to south?
If my understanding is correct, the former. IIRC, the discussion around US 666's renumbering to US 491 was that US 666 was simply the sixth US 66 spur.
Quote from: xonhulu on September 04, 2010, 01:21:00 AM
Quote from: Bickendan on September 04, 2010, 01:09:47 AM
Quibble: US 26 in Oregon is exactly where it should be: Between US 20 and 30. It's US 20 and 30 that are in the wrong order; swap them and everything's fine.
But there's little to no point to swapping them, as doing so wouldn't be doing the Public At Large any service (they don't care about the route order), the cost to swap the signs wouldn't be justified, the Historic US 30 shields on OR 100 would make no sense at all, and given that AASHTO would have to sign off on this, I really wouldn't want to give them ammo to force the decommissioning of the US 30 corridor in Oregon on the grounds that it largely duplexes with I-84 and forcing OR 2 to be signed from Astoria to Portland with Bus I-84 taking US 30's place east of Portland. *shudders*
I doubt very much in that scenario that they'd call it OR 2. My guess is they'd call it OR 30, like they did when they decommed US 99 and US 126 years ago. If not, then I'd guess they'd go with OR 92, making the Route Number match the Highway Number.
The highway number is 2W, as it's still the Columbia River Highway.
I'm not really a fan of numbering spurs based on the order they were built. I'd prefer a system where, in each given state, the westernmost 3di is numbered 2xx, then the second westernmost is 4xx, etc. Then the southernmost would be 1xx, while 9xx would be the northernmost.
Quote from: Bickendan on September 04, 2010, 01:44:52 AM
If my understanding is correct, the former. IIRC, the discussion around US 666's renumbering to US 491 was that US 666 was simply the sixth US 66 spur. [The highway number is 2W, as it's still the Columbia River Highway.
I'm pretty sure they changed it to 92, although ODOT's documentation is pretty mixed. The HSHO document lists it in the table of contents as Hwy 2W, but when you go to the actual page, the title heading says "Lower Columbia River Hwy (92)." The source I consider most definitive is the 2009 State Hwy Map on ODOT's website (link: http://egov.oregon.gov/ODOT/TD/TDATA/rics/docs/2009_State_Hwy_Map.pdf ) and it designates the highway as 92, so I go with that.
I actually hope it is still considered Hwy 2W if your scenario comes true, as OR 2 would be a better number than OR 92, but once again I think they'd just make it OR 30. Of course, my real preference would be to retain US 30. If it came down to AASHTO trying to force its decommissioning, I'd prefer one of the following scenarios:
1. Oregon and Idaho ignore AASHTO and keep US 30 as it is;
2. Washington signs US 30 on WA 14 to Umatilla, then Oregon routes it on either US 395/I-84 or US 730/OR 37 to Pendleton. Idaho could also restore US 30 to some old alignments.
I don't think US-30 is going away. It might be concurrent with I-84 for almost its entire length in Oregon, but overall, the concurrency is a fraction of US-30's total length. I don't see why AASHTO would mess with US-30 in Oregon at all.
Quote from: Quillz on September 04, 2010, 02:28:31 AM
I don't think US-30 is going away. It might be concurrent with I-84 for almost its entire length in Oregon, but overall, the concurrency is a fraction of US-30's total length. I don't see why AASHTO would mess with US-30 in Oregon at all.
Yeah, I don't see it happening, either. The application to decommission would have to be made jointly by OR and ID, and I've never seen any sign that those states want to do away with it. They still seem to find the route useful.
Quote from: agentsteel53 on July 25, 2010, 10:27:05 PM
Quote from: yakra on July 25, 2010, 10:21:11 PM
Well, US5 just happened to be at a very thin part of the country.
I'm just imagining how much difficulty Chile would have in developing a grid-based system. How do they manage their numbering?
Can you read Spanish?
http://es.wikipedia.org/wiki/Rutas_nacionales_de_Chile
If I'm understanding this right, single-digit numbers are reserved for "longitudinals" - north-south routes above a certain minimum length, then everything else is by region or province (10s are in one area, 20s in the next.... looks like these numbers increase from north to south, or rather number classes increase from north to south - the 10s being in the northernmost part of the country and so on.)
Quote from: TheStranger on August 31, 2010, 12:28:06 AM
Actually, I think the US route system had one huge advantage over the Interstate system: flexibility.
Other than the x1 and x0 routes (and to some extent x5), anything else could be as diagonal as necessary. Often times this was taken to excessive extremes (52, 62, 68, 33, 35) but usually this allowed for 2 digit routes to be placed wherever needed, as opposed to the issue the Interstates have of running out of 2 digit numbers due to the grid being too closely laid out.
best comparison? US 11, as opposed to I-81 and I-59 being two entirely seperate interstates on different planes of that grid, following that one corridor.
Having said that, does that explain 44 and 46 being WAY out of the grid? X-( And how about 59/96!?
44 and 46 were relative latecomers. (I've seen early-30s maps of the region which don't show them.) I suppose someone decided there needed to be two-digit routes there and they...picked numbers out of a hat? (Is it possible that 44 was the lowest number available?) So they're analogous to how we got I-99. And how many people here remember that when I-68 was built, it was called US 48?
Quote from: Quillz on September 04, 2010, 02:17:39 AM
I'm not really a fan of numbering spurs based on the order they were built. I'd prefer a system where, in each given state, the westernmost 3di is numbered 2xx, then the second westernmost is 4xx, etc. Then the southernmost would be 1xx, while 9xx would be the northernmost.
The "I" in "3di" stands for Interstate. A three-digit US route is more properly called a 3dus.
In US 66's case, I know the easternmost branch was 166, then 266 split off further east, then 366, and 466 was in CA. I was under the impression that 666 was an original US route, however, so it would be the pattern breaker there.
I'm thinking there really wasn't too much thought given to it.
Quote44 and 46 were relative latecomers. (I've seen early-30s maps of the region which don't show them.) I suppose someone decided there needed to be two-digit routes there and they...picked numbers out of a hat? (Is it possible that 44 was the lowest number available?)
It wasn't. US 38 was an original route but became available in 1931. US 28 was also dropped in 1934, the same year US 44 came into existence.