State Highway grids

[Duke87]

Connecticut originally had a system where it numbered primary state highways as 1xx and secondary state highways as 3xx (with one and two digit numberes being reserved for New England's interstate routes). But then the state went and renumbered basically everything and now there isn't much particular rhyme or reason to the numbering - although there is still a general trend that the lower the number, the more major the route, and there is still sometimes a tendency to group things somewhat (best example is how CT 77, 79, 81, 83, 85, and 87 are all north-south routes which run roughly parallel to each other in that order).

There is still a solid system for the unsigned routes, though. 4xx routes lead to a state-owned facility of some sort (park, airport, train station, etc.). 5xx, 6xx, 7xx, and 8xx are in ConnDOT regions 1 through 4, respectively (though the region borders don't match up with county lines at all and if you look at them on a map there is no apparent sense to why the borders were drawn the way they are). 9xx routes are just really short bits of road that are state maintained.


New York, again, has no real pattern to its signed routes, but the unsigned ones have a system. In this case, all unsigned "reference routes" are three digit numbers beginning with 9 followed by a letter. The tens digit is the region number (so, for instance, route 983D is in region 8).

[route56]

You can't really tell with Kansas. You can see a potential grid pattern if you go from east to west. But it's not entirely in order (K-3 west of K-7; K-14 between K-17 and K-19), some numbers aren't in said grid (K-21) and it would appear to have been created after the U.S. routes were planned because U.S. highways are in between state routes that themselves are consecutively numbered (U.S. 83 being in between K-23 and K-25).

There appears to be no sort of pattern in the east-west state routes. K-96, specifically, has nothing to do with a grid.

Actually, K-21 was in your grid... it was the original designation of US 283.

Also, remember that US 183 and US 281 were origionally designated as K-1 and K-8, respectively. Oh, and don't forget that K-99 and K-177 were originally K-11 and K-13

[txstateends]

I don't think TX has ever had a definite route allocation system, especially since the late 1930s.  From the best I can tell, without proper research, it looks like from older maps I've seen, that 1- and 2-digit numbers were generally assigned to longer routes, while 3-digit numbers were given much shorter ones.  Other than that, I've seen no E-W/N-S arrangements, no incremental assignments, nor even-odd arrangements among the placements.  The closest thing to a parent-child (a-la the US highways) instance was (and still is) TX 236 turning off of TX 36 in central TX, west of I-35.  I've never heard whether this was intentional, or not.

Usually the state is pretty good about not putting a state highway near a same-numbered US, Interstate, or other numbered highway, with a couple of known exceptions.  TX 70 crosses US 70 (and US 62) in Matador, while FM 121 in Grayson County (north of Dallas) comes very close to TX 121 in Collin and Fannin Counties.  I would think, as big as TX is, that there's plenty of room to avoid any possibility of confusing same-numbered intersections, including the 2 examples above.  Now as for the future intersection of I-69 with US 69 near Lufkin in a few years, ummm, well, let's just say they didn't ask my opinion about it first 

[vdeane]

New York, again, has no real pattern to its signed routes, but the unsigned ones have a system. In this case, all unsigned "reference routes" are three digit numbers beginning with 9 followed by a letter. The tens digit is the region number (so, for instance, route 983D is in region 8).

According to wikipedia, NY's route numbers were assigned in clusters based on geographic location, though that's not followed today.

[sp_redelectric]

Here's a trivia question for you: prior to the OR 138 change and the advent of the 2002 routes, where were the only places in Oregon where a route had the same number as its hidden highway designation?

Both of them involve U.S. 26:  From the Ross Island Bridge east to the junction with Oregon Route 35 is Highway 26.  (U.S. 26 becomes the Warm Springs Highway 53 southeast from there, while Mt. Hood Highway 26 follows Oregon Route 35 north to Hood River.)

U.S. 26 west of downtown Portland is the Sunset Highway 47.  Between Banks and Manning, Oregon Route 47 is multiplexed with U.S. 26.  North of Manning and in Banks south to (but not beyond) Forest Grove, however, Route 47 is the Nehalem Highway 102.

[xonhulu]

Both of them involve U.S. 26:  From the Ross Island Bridge east to the junction with Oregon Route 35 is Highway 26.  (U.S. 26 becomes the Warm Springs Highway 53 southeast from there, while Mt. Hood Highway 26 follows Oregon Route 35 north to Hood River.)

U.S. 26 west of downtown Portland is the Sunset Highway 47.  Between Banks and Manning, Oregon Route 47 is multiplexed with U.S. 26.  North of Manning and in Banks south to (but not beyond) Forest Grove, however, Route 47 is the Nehalem Highway 102.

Good job!  You got both of the cases I was thinking of, and I'm pretty sure there were no other examples.  Both are coincidences, AFAIK, especially the first example, since when the Mt Hood Hwy #26 was designated in 1917 there's no way they could've foretold US 26's creation in 1926 or its 1952 extension to Oregon.  The OR 47 duplex with Sunset (Wolf Creek) Hwy #47 is much older, I believe, dating to the creation of the Oregon Route System in the early 30's.

[The High Plains Traveler]

New Mexico (in 1912) used a version of consecutive numbering, in which the longest and most important routes received the lowest numbers.  NM 1, NM 2, and NM 3 all exist within their original corridors, for example, but have been greatly truncated in length because they were largely supplanted by the US highways.  New Mexico did not move to a system as such until the major renumbering of 1988, in which lengths of state highway which were renumbered to remove concurrencies (which were not allowed under new policy) had the NMDOT district number as the first digit in the new three-digit number.

NM-1 disappeared after 1927 in favor of U.S. 85, when the "modern" New Mexico route system was established to accommodate the U.S. routes. It reappeared in the early-1970s after completion of I-25 between T or C and San Antonio, when it was assigned to old U.S. 85 in that lightly traveled stretch. NM-2 continued in existence until the early 1930s when U.S. 285 was established, disappeared for a couple of decades, then was assigned to a stretch of old U.S. 285 between Roswell and Artesia. This road was also designated U.S. 285 Alternate.  I saw both NM-1 and NM-2 posted in the mid-70s when I lived in New Mexico; I know, Jonathan, you have cited documentation that New Mexico assigned NM-1 in 1988, but it was posted long before that.

NM-3 has been in continuous existence since the 19-teens, but no piece of present-day NM-3 exists along the original NM-3 corridor. That original route is U.S. 70 east of Las Cruces, U.S. 54 to Tucumcari, and old U.S. 66 east of there. One original route that I'm pretty sure exists today exclusively along its historic alignment is NM-41.

One big weakness with the new system of first digit for DOT district is that it isn't consistent; many routes continue to carry their pre-1988 designation, so there is no perceived value in clustering of the routes that were renumbered or newly designated at/after that time.

[luokou]

It's actually a little more specific -- they are related to the county the highway originates in, starting in the NW corner and working south, then east.  Hence, Clatsop County hwys are #10x, Columbia County's are #11x, etc, up to Malheur County's #45x's. (Note that Oregon has 36 counties.)  That generally matches the ODOT regions, but not like what you wrote.  For example, Marion County has the 16x's, Lincoln County has 18x's and Polk County has 19x's, and those are all region 2, not Portland Metro!

Then there seem to be some very recent numbers applied to spurs/loops in the 48x's and 49x's.  None of these correspond to any route numbers.

Very enlightening! I didn't know the post-2000 numbers had finer divisions as such. I did notice that the numbers generally tended to fit in ODOT regions, but I was hastily looking over the official map and doing some broad matching before running off to work. Thanks for the information!

[The High Plains Traveler]

From the first few numbers, the 1934 numberings:

2 - still in the original spot it was, Santa Monica Boulevard and Angeles Crest Highway, though west segment was an extended portion of US 66 from 1937-1964
3 - today's Route 1 from Ventura to San Juan Capistrano

4 - same spot
5 - today's Route 35 in the Bay Area

6 - now-defunct state route along Bolsa Avenue in Orange County

The original CA-6 actually ran along what later became CA-26, Olympic Blvd., except that it used Pico Blvd. at Santa Monica. The short-lived designation for Bolsa Avenue in Orange County was CA-26. Obviously, CA-6 was renumbered when U.S. 6 was extended into California in 1936.  If you look at the 1934 L.A. area map you can easily see the system of adjacent routes separated by 4, which was the original numbering scheme throughout California: 2, 6, 10, 14, 18, 22 and 26; and north-south: 3, 7, 11, 15, and 19. 

[xonhulu]

Very enlightening! I didn't know the post-2000 numbers had finer divisions as such. I did notice that the numbers generally tended to fit in ODOT regions, but I was hastily looking over the official map and doing some broad matching before running off to work. Thanks for the information!

I should add this pattern seems to have two "bands:"  west of the Cascades and east of them.  Within each band the numbers increase by county first eastward, then southward.

[TheStranger]

From the first few numbers, the 1934 numberings:

2 - still in the original spot it was, Santa Monica Boulevard and Angeles Crest Highway, though west segment was an extended portion of US 66 from 1937-1964
3 - today's Route 1 from Ventura to San Juan Capistrano

4 - same spot
5 - today's Route 35 in the Bay Area

6 - now-defunct state route along Bolsa Avenue in Orange County

The original CA-6 actually ran along what later became CA-26, Olympic Blvd., except that it used Pico Blvd. at Santa Monica. The short-lived designation for Bolsa Avenue in Orange County was CA-26. Obviously, CA-6 was renumbered when U.S. 6 was extended into California in 1936.  If you look at the 1934 L.A. area map you can easily see the system of adjacent routes separated by 4, which was the original numbering scheme throughout California: 2, 6, 10, 14, 18, 22 and 26; and north-south: 3, 7, 11, 15, and 19. 

Thinking about Norcal for a second, trying to see if this applied:

4 (still in same route today)
8 (now Route 88 in Stockton)
12 (same route today)
16 (mostly same route today)
20 (same route today)
24 (truncated from its fullest extent but still exists)
28 (This, I'm curious about: it became signed route 128 but not sure the pre-1950s Route 28 ever even was signed)
32
36

don't think there ever was a state route 40

44 has been realigned significantly but still exists near original corridor

original 48 I don't think was a 1934 route

For the odds...
5 (now 35)
9 (truncated but still exists)
13 (original 13 became 17)
21 (don't think this is from 1934 though)
25 (still exists)
29 (exists)
33 (more of a cross-state route, still exists)
37 (still exists but realigned)
41
45
49
53 (was this originally from 1934?  shortened since 1964)

[NE2]

http://www.gbcnet.com/roads/ca_routes_1934.html

[Quillz]

The modern CA-33 is mostly from the 1964 renumbering, though. Much of it replaced the old US-399.

[TheStranger]

The modern CA-33 is mostly from the 1964 renumbering, though. Much of it replaced the old US-399.

Not necessarily.  The portion of Route 33 north of Route 166 (to I-5) is approximately original to what the route was in 1934, and is way longer than the ex-US 399 segment ever has been.

[Mapmikey]

The previous description of North Carolina's original system is not quite accurate...

The major routes in the beginning (1920 or 1921) did end in 0 but direction was not a consideration:

NC 10 EW - US 19 S of Asheville, US 70 e of Asheville
NC 20 EW - US 70 W of Asheville, US 74 E of Asheville
NC 30 NS - US 17 S of Windsor, several routes n of Windsor
NC 40 NS - US 117, US 301 n of US 117
NC 50 NS - US 1
NC 60  diag - US 421
NC 70 NS - several routes, notably US 220
NC 80 NS - US 52 S of Salisbury, US 601 N of Salisbury
NC 90 EW - US 64 E of Raleigh
These routes then had daughters in a grid:
For example, NC 10's daughters were situated in an E to W grid:
NC 11
NC 12 (now mostly US 258)
NC 13 (US 501 N of Durham)
NC 14 (now NC 86)
NC 15 (US 29 S of Salisbury)
NC 16 (US 321 Bus, etc S of Conover)
NC 17 (US 321 N of Hickory)
NC 18
NC 19 (mostly US 221)

Some x0 routes skipped numbers in their daughter schemes and x5 was not particularly special nor necessarily N-S running.

The daughters, plus the x0 routes also had 3 digit daughters which initially also were placed in a progressing grid:
NC 101
NC 102 (generally US 13 near Goldsboro)
NC 103 (now NC 119)
NC 104 (now NC 80)
NC 105 (NC 126 and abandoned route northward)
NC 106 (now NC 107)
NC 107 (US 441 n of Dillsboro)
NC 108 (now US 129 n of US 19)
NC 109 (US 64 murphy to Hayesville)

NC 20 actually had so many spurs that it used 21x numbers too.

Eventually before the state scrapped their system in 1934 they had to make exceptions like NC 31 in Mars Hill (but it had a NC 311 spur)...

The earliest NCDOT map of NC with the numbers on it can be accessed here (1922) - http://dc.lib.unc.edu/cdm4/item_viewer.php?CISOROOT=/ncmaps&CISOPTR=1802&CISOBOX=1&REC=9

Mapmikey

[Riverside Frwy]

A best example I saw of state highway numbering was old CA-30 before it was turned into CA-210. There is a spur, CA-330, east of San Bernardino.

CA-55 and CA-57 also seem be on some kind of grid. Both routes are close, hence, the close numbers and then they are both odd, going North to South.

Same for CA-56, CA-52, and CA-54 near San Diego. (Relatively) Close together and both are even as East-West routes.

Only three examples of numbering I saw that made any sense.

[froggie]

One that hasn't been mentioned yet is Mississippi.  Mississippi has a fairly (all things considered) uniform numbering system for their state highways.  Two notes to start with:  all north-south routes are odd-numbered while all east-west routes are even-numbered (though there's a couple routes, MS 315 in particular, that in reality break this standard).  Also, the US highway system predates Mississippi's state numbered routes, so there never was a MS 11, MS 45, MS 49, MS 80, MS 84, etc etc.

The 1/2-digit routes are also sequenced into a grid for the most part.  Odd-numbered routes begin with MS 1 in the western part of the state and increase to MS 19 in the east.  The odd MS 2x routes are a bit jumbled, but the process begins again with MS 33 in the southwest and MS 41 in the northeast (there is no MS 31).  Technically another process continues with MS 43 being west of MS 47.  The odd MS 5x routes used to exist along/near the Mississippi Gulf Coast, starting with MS 53 in Hancock County and continuing to MS 63 in the east.  When the Interstates came, old MS 55 was renumbered MS 67, old MS 57 became part of an extended MS 15, and old MS 59 became the new MS 57.  MS 69 near Columbus sort of fits this MS 5x-6x scheme.

The even routes begin with MS 2 in the north and continue to MS 26 in the south.  When the Interstates came, old MS 10 became MS 50 and old MS 20 became MS 28.  MS 22 is not an original route...it was added ca. 1950, hence why it breaks this part of the grid.  The process begins again with MS 30 in the north and continuing to MS 48 in the south, but there's a noted discrepancy here:  MS 46.  Also, MS 44 is a bit of a discrepancy, being south of MS 48, but it's not an original route and was added later.

MS 1xx routes are former US route alignments that the state wished to keep on the state highway system.   There is also a MS 2xx route:  MS 245, which is the former alignment for ALT US 45.  A MS 249 has been proposed in the Jackson area, but has not been approved by the legislature.

Mississippi's 3-digit routes are also organized geographically based on their first digit.  MS 3xx routes are in northern Mississippi, generally north of US 82.  MS 4xx routes are in north-central Mississippi (generally between US 82 and US 80), while MS 5xx routes are in south-central Mississippi.  MS 6xx routes are in the 6 counties adjacent to the Gulf Coast.

Mississippi's generally-hidden-but-occasionally-signed routes are also organized geographically:  MS 7xx routes in northern Mississippi, MS 8xx routes in central Mississippi, and MS 9xx routes in southern Mississippi.  The highest route number is MS 992 in Picayune.

[TheStranger]

A best example I saw of state highway numbering was old CA-30 before it was turned into CA-210. There is a spur, CA-330, east of San Bernardino.

CA-55 and CA-57 also seem be on some kind of grid. Both routes are close, hence, the close numbers and then they are both odd, going North to South.

Same for CA-56, CA-52, and CA-54 near San Diego. (Relatively) Close together and both are even as East-West routes.

Only three examples of numbering I saw that made any sense.

Post-1964 route clustering:

- Route 82, 84, 85, 87 all established in the Bay Area
- Routes 236, 237, 238 are all ex-Route 9
- today's Route 242 (ex-Route 24) is not far from unbuilt Route 239.
- Post-1964 Route 31 was in the same vicinity as 1950s-2005 Route 30
- Today's unsigned Route 164 (which really should just be reverted to Route 19) is in metro LA, where the original 1964 Routes 159, 163 and 165 were as well
- Routes 78 and 79 are original to the 1934 state highway system; Route 75 was added to metro San Diego in the 1940s, and Route 76 in the 1950s
- Routes 72 and 73 were added in Orange County near 1934-era Route 74
- Unbuilt routes 143 and 148 both were planned to run towards the Sacramento suburb of Elk Grove

Route 55 is original to the 1934 grid, with 57 being created in 1964.

[pianocello]

Illinois' system started out with SBI (State Bond Issue) routes that later became the state route numbers. The first wave in 1918 were routes 1-46 and the second in 1924 involved route 47-185. I can't really tell any rhyme or reason to the numbering scheme from Rich Carlson's descriptions, so my best guess is that the more important routes received the first Bond Issues, and therefore the lower numbers.

I don't know very much about the Iowa system, but it looks like the more important routes had the lowest numbers.

EDIT: After putting the first 15 or so IL SBI routes onto a map, I was able to determine that:

• All of the primary cross-state routes seemed to be covered on the map
• 1-3 were N-S, increasing from east to west
• 5-13 were E-W, increasing from north to south
• 4 was also N-S, but it was diagonal (became US-66)

The rest were relatively minor and, like previously mentioned, were grouped by region.

[triplemultiplex]

South Dakota has a very well established grid of two digit state highways that mirrors the US highway grid.  (odd numbers N-S increasing east to west and even numbers E-W increasing north to south).  They seem to have left a lot of room for expansion in that grid if they ever wanted to since they skip many numbers.
Many of their 3 digits state highways are numbered as spurs, but many others are just random.

[The High Plains Traveler]

A best example I saw of state highway numbering was old CA-30 before it was turned into CA-210. There is a spur, CA-330, east of San Bernardino.

CA-55 and CA-57 also seem be on some kind of grid. Both routes are close, hence, the close numbers and then they are both odd, going North to South.

Same for CA-56, CA-52, and CA-54 near San Diego. (Relatively) Close together and both are even as East-West routes.

CA-330 is a former piece of CA-30 which ran into the San Bernardino Mountains there. 30 was re-routed down to I-10 at Redlands before 210 came into existence. The 330 designation is analogous to CA-371, a former piece of 71. I think those are the only CA-3xx routes in California.

CA-55 is an original or nearly original numbered state highway, while 57 is a relatively new route that didn't exist before the 1960s. I don't know if that designation had been assigned at the time of the 1964 renumbering. It's possible it was selected as an available route adjacent to 55. I think the same logic applies to 52, 54, and 56 near San Diego, none of which existed before the 1960s and are probably post-1964 routes. It's a good guess the numbers were assigned (ultimately by the Legislature but proposed by CalTrans) because of their adjacency. I don't think the odd-even factor enters in since 1964, however; there are even N-S and odd E-W routes.

I'm a little intrigued by the two oddball routes in the original 1934 plan: 740 was an obvious extension of 74, separated by a piece of U.S. 395 between Elsinore and a point east of there where 395 went north (this was eventually bypassed by 395 and became 74 only); and 440, from Redding to Lassen Park even though there wasn't a 44 in the original postings. I think those disappeared within a year or two - anyone have a better map collection from this era than I?

[Kacie Jane]

Washington has a far more complicated grid than just the spur numbering- the north south routes increase from west to east- 3 is the westernmost and 31 is the easternmost, the exception being SR 19. US-101 is functionally SR 1, US-97 is SR 15, and US-395 is SR 29 (and therefore does break the grid in a couple spots.)

East west routes increase from  south to north in the western part of the state, and then again in the eastern part- as you go north from the SW corner, you get SR 14, 4, 6, 8, 16/410, 18, 20. Then start again on the east side- 22, 24, 26, 28. 14 is the exception, but that was caused by the US-830 designation. US-12 used to be SR 14 where it wasn't 410, and that fits the grid. 10 doesn't either, but that's because it's old US-10.

Minor quibble.  I'm fairly certain there are 3 strips of east/west routes, not two as you describe.

As you mention, when the current routes were numbered in 1964, US 12 was still four or five years from being extended into the state, and US 830 was still four or five years from being decommissioned.  So, in the original plan, not only did you have SR 14 further north where US 12 is today, but you also had US 830 being functionally SR 12 (example: what is now SR 141 was originally SR 121).

(Note that where you say, "US-12 used to be SR 14 where it wasn't 410, and that fits the grid," that's not true as you describe it, since it's south of SR 8 -- both the new and original versions.)

So I think there's three strips... western (SR 4, SR 6, SR 8 ), central (US 830/SR 12 (now SR 14), SR 14 (now US 12), US 410/SR 16, SR 18, SR 20), and eastern (SR 22-30, 30 being the original number for the eastern half of SR 20).

Also, you mention SR 19 as an exception added later, but SR 11 was also added slightly after the original plan, and is slightly out of the grid west of SR 9.

[NE2]

440, from Redding to Lassen Park even though there wasn't a 44 in the original postings.

44 quickly became US 299, and 740 initially extended north on US 395 to Riverside. (US 395 south of Elsinore was 71.)
http://www.gbcnet.com/roads/ca_routes_1934.html

[jwolfer]

New Jersey 5xx county routes are in a  N-S grid more or less with 502 in the north to 540 in the south.  But above 540 is random.

There seems to be some clustering 20s around Newark ( 20 21 22 23 24 28),  30s radiating out of Trenton and in Monmouth and Ocean Counties( 31 32 33 34 35 36 37). 40s radiate out of Camden.. (40( now 70) 41 42 44 45 47)

But any grid to state highways seems to have been abandoned.

[empirestate]

New York, again, has no real pattern to its signed routes, but the unsigned ones have a system. In this case, all unsigned "reference routes" are three digit numbers beginning with 9 followed by a letter. The tens digit is the region number (so, for instance, route 983D is in region 8).

According to wikipedia, NY's route numbers were assigned in clusters based on geographic location, though that's not followed today.

New York's original touring routes in 1924 had odd numbers for E-W routes and even numbers for N-S routes. E-W routes had a very loose progression from north to south...excluding NY 1, which by an odd mix of design and coincidence is now US 1. The rest, NY 3, 5, 7, 9, 13, 15, 17 were pretty much in order. 11 was oddball, being north of NY 5. Then you jump back a bit for 19, 21...23 is out of place...and then 25 and 27 which are still there on Long Island.

For N-S routes, you had NY 2 and 4, then from east to west you had NY 6, 8, 10, 12, 14, 16, 18...20 was oddball...then jumping back to the east for 22, 24, then sorta-kinda in order into the 30's.

Whatever the system was, was pretty much obfuscated first by the addition of US highways in 1927, then by the 1930 re-numbering, then again by US highway changes in the mid-30s. Still, a surprising number of vestiges remain, most notably 12-14-16-[18*] (and the current 8 and 10 were later additions that fit into this pattern, whether by design or not).

*The original NY 18 was a N-S route at the west end of the state, from Buffalo south. Later it was extended up along the Niagara River, still in keeping with the system. Today, it's almost all E-W and lies north and east of its original course, but the N-S piece in Niagara County still holds true. It's actually pretty fascinating how that route has oozed continually along like a meandering river, never with any actual discontinuity from its former self!

UPDATE: I've uploaded a scan of the Automobile Blue Book map from 1925 showing NY's state routes of the time (the original system). This map was copyrighted in 1925 and to my knowledge the copyright has not been renewed, so here it is:

http://empirestateroads.com/maps/NY1925.jpg (full resolution, 11.2 Mb)
http://empirestateroads.com/maps/NY1925low.jpg (lower quality, same size, 2.7 Mb)