State numbering

[DrZoidberg]

We're all familiar with the numbering of both the US and Interstate highway grid, but what about state highways?  I'm sure this varies by state, but do any states follow a "grid" of their own?  Do they number based on the order in which they were built? A lot of states seem to just number at random, based on atlases I've read.

Also, when building a 3-di, do states often go in numerical order? (i.e. your first even number 3-di would be 2xx, then 4xx, and so on).

[Michael]

New York doesn't follow a grid, but they do have some practices that they follow:

• A freeway extension of an Interstate spur is the same route number, but a state shield.  For example, the extension of I-690 in Syracuse is NY 690.


• The x90 spurs increase from 190 to 890 west to east.  The exception is I-990 in Buffalo.


• Reference routes (state maintained roads with a hidden number) are in the 900 series, with the second digit being the region number.

Here's a map with the DOT regions in NY:

[FLRoads]

Florida has a "grid" system that was created in 1941 (it replaced their former system) and implemented in 1946.

North and south roads end in odd numbers with the lowest number being on the east coast (Florida A1A for example) and the highest being on the western most section of Florida (namely Florida 99 - now Escambia County 99). East/West routes bear even numbers with the lowest number in the northern part of the state (Florida 2 for example) and the highest number in the south (Florida 90-a.k.a. US 41 for example). Even numbered routes that end in 0 (like Florida 20) typically run across the state and further split the grid system into segments.

See the example below for a more in depth explanation of the state grid system.



Click here also.

And by the way, A1A is so named due to its close location to US 1, so as not to confuse the two routes.

[Revive 755]

Indiana and South Dakota are the only states that I know of that seem to try and number their state highways in a grid pattern using the same numbering rules as the US routes follow.

[corco]

Washington runs on very strict system where  two digit east-west state routes run south to north in two columns and two digit north-south run west to east in increasing  intervals. Three digit routes use a branch numbering scheme, so routes off SR 27 are SR 27x. Routes off interstate 5 are SR 5xx, usually increasing south to north or west to east, routes off US-12 are 12x

Wyoming has no real scheme for long haul routes but numbers its local routes by county in alphabetical order, so Albany County has routes 10-14, Carbon County has routes 70-78, Goshen County has 151-161, Platte has 310-321, etc

Idaho theoretically clusters with 5x numbers up north, single digit numbers up north, 7x numbers down south, 8x numbers in the southeast, etc, but it is very loosely adhered to

[Voyager]

California...has nothing.

[Alex]

Delaware east-west routes mainly increase as one heads south (Delaware 4 was once an east-west route between Middletown and Odessa, but its relocation is still below Delaware 2.), the north-south routes loosely do the same from east to west (Delaware 1 was added over Delaware 14 later, Delaware 9 originally ended south of Odessa, so it was never east of Delaware 7 until it was extended).

Delaware imports several numbers from Pennsylvania and Maryland. They even imported New Jersey 48 when the two were connected via ferry.

With all that stated, the state got a kick with x2's: 42, 62, 72, and 92, which I've never really understood why. Delaware 71 is an import remnant from Maryland 71. Delaware 23 was the most recently added two-digit route. I don't know how Delaware 44 got its number.



Maryland uses a route-clustering system based upon the county. Mike Pruett has a good description of it here.

[Alex]

California...has nothing.

Yes... but sort of in the same realm, when California adds a new state route, they use the lowest number available. When a number is decommissioned, its thrown into the pot for future use. So California 7 is on its 3rd version, and California 11 is supposed to come back yet again too.

[Voyager]

Hmm, I never knew that.

[mightyace]

All I know at the moment about Tennessee is that they cluster their secondary route numbers.  [see my post in the Numeric Highway Game for TN 246-248.  Other TN secondaries from 240-25x are in the middle TN area south of Nashville.

I'm not saying there isn't a pattern for the primary state routes, but I don't know what it might be.

[mapman]

California did at least start with a system.  Initially, it had a "some for you and some for me" system, whereby consecutive numbers or groups of numbers were split between Northern and Southern California (e.g. CA 2 in SoCal, CA 3 through 5 in NoCal [CA 5 is now CA 35, I think], CA 7 in SoCal, etc.).  But now, yes, it's pretty random.

[Duke87]

Connecticut originally numbered major routes in the 100s and minor routes in the 300s. This system was long ago scrapped. Now, state routes are numbered from 1-399 (but the same number as a US route or Interstate present in the state is never used) and unsigned state-maintained segments of road are numbered from 400-999, with 400's used for routes leading to state facilities, 500's, 600's, 700's, and 800's used for other routes in each of the four transportation districts of the state, and 900's used for miscellaneous little odds and ends.

And, actually, many state route numbers east of the Hudson inherit their numbers from an old, pre-US highway system attempt on the part of states up there to come up with a system of highways for New England. Different from current standard practice, they made even numbers north-south and odd numbers east-west. Then the US highways system showed up and they scrapped the whole thing, with some of the routes getting absorbed into US routes and others becoming just state routes. But this is, for instance, where the numbers for NY 22, CT/MA/VT 8, CT/MA/NH 10, CT/MA/NH/VT 12, CT/MA/NH 32, VT/NH 9 (and NY 7, they changed their number), and explains why those routes are so long and continue their numbers across (sometimes multiple) state lines.
In theory the numbers 1-99 were reserved for this (hence the state routes in the 100's and 300's thing).

[DrZoidberg]

Yes... but sort of in the same realm, when California adds a new state route, they use the lowest number available. When a number is decommissioned, its thrown into the pot for future use. So California 7 is on its 3rd version, and California 11 is supposed to come back yet again too.

I think Wisconsin does something similar, as WI-15 is in its 3rd or 4th version (at one point it was what's now I-43 between Milwaukee and Beloit)

[SSOWorld]

Yes... but sort of in the same realm, when California adds a new state route, they use the lowest number available. When a number is decommissioned, its thrown into the pot for future use. So California 7 is on its 3rd version, and California 11 is supposed to come back yet again too.

I think Wisconsin does something similar, as WI-15 is in its 3rd or 4th version (at one point it was what's now I-43 between Milwaukee and Beloit)

Not sure about that with Wisconsin, but I do know they don't use single digit route numbers.  WI has a rule of not duplicating routes - a rule that was violated twice already:

• I-39 with a WIS 39 already signed (albiet in two totally unrelated locations)
• WIS 794 (Milw Lake Parkway) as an "extension" of the already existing I-794

Of course there will probably be another violation once I-41 is implemented (if it is)

[DrZoidberg]

When I lived in Wisconsin, the type of "system" I saw was all the primary highways were numbered 11-99, and then "lesser" or small spur highways were between 100-199.  There were exceptions, but I don't recall too many highways north of 200 (241, 341, 441, and 794).

[SSOWorld]

When I lived in Wisconsin, the type of "system" I saw was all the primary highways were numbered 11-99, and then "lesser" or small spur highways were between 100-199.  There were exceptions, but I don't recall too many highways north of 200 (241, 341, 441, and 794).

Yeah that make sense.

It seems the ones of 200 and above are sort of spur routes

• 241, 341, 441 off US 41
• 213 off WIS 13 (signed when WIS 13 was extended all the way to Beloit(?) - course WIS 13 now ends in the Dells
• 312 (Eau Claire North Crossing) off US 12
• 253 (Spooner) off US 53
• 351 (Janesville) replaced by WIS 11 off US 51
• 794 - self explanitory

[akotchi]

I'm not sure what Pennsylvania does as a state, but there seem to be a few 3-digit state routes (3ds?) that are "children" of a 2-digit route, whether state or U.S.   In my area are SR 213, 413 and 513 in the vicinity of U.S. 13; and SR 132, 232, 332, and 532 that are near to SR 32.

We have our share of state routes that fit in the interstate grid, such as 581, 283 (though there is an I-283), 378 (from a former routing of I-78).

We also have a number of state routes that were old U.S. routes of the same number, such as 611, 309, 230.

[TheStranger]

When the Great Renumbering occurred in 1964, California's seemed to start to use as many numbers (sequentially) as possible for a while, the best example being these former portions of Route 9: Route 236 in the Santa Cruz mountains, Route 237 in the South Bay, and Route 238 in the East Bay.  There's also a sense of regional clustering, as was in the original system (i.e. 84 and 85 are in the Bay Area, as are 35 and 37, and 92 and unbuilt 93; 38 and 39 are both in the metro Los Angeles environs).

Route 330, 371, and 242 all are based off of former designations (30, 71, and 24 respectively).

The Foothill toll roads in Orange County had their own system (231, 261, 241, of which 231 no longer exists)

The state looks like it tries to avoid numbers 300 and above as much as possible.  It also only generally follows even-odd rules; Route 14 (an even number) is north-south, replacing old US 6's westernmost extent (an east-west route running north south).  Route 91 is east-west because it was one of the southernmost segments of US 91 at one time.  Not sure why 82 and 72 were chosen for old segments of US 101.

Originally, higher numbers were preferred for the rural counties, still evidenced with some long-standing east-west route numbers in the Central Valley (152, 180, 166, 120) and with some post-1964 routes there too (137, 155, 201, 219 - all of which do not follow the even/odd rule at all). 

[Voyager]

Yeah, I guess you're right about that...29 is also in the bay area, and didn't 121 used to be based off of 21 before 680 replaced it? Also, many of the lower numbers are in the bay area, most of the numbers between 4-87 are mostly scattered around there.

[TheStranger]

Yeah, I guess you're right about that...29 is also in the bay area, and didn't 121 used to be based off of 21 before 680 replaced it? Also, many of the lower numbers are in the bay area, most of the numbers between 4-87 are mostly scattered around there.

121 is old 37 actually (37 has the odd # for east-west probably because the western segment used to be part of a north-south route).

Bay Area #s under 100: 4, 9, 12, 13, 17, (21), 24, 25 (kinda), 29, 35, 37, 61, [77], 82, 84, 85, 87, 92, [93]

[Voyager]

Yep, 37 used to go to Napa and 48 used to take the current route.

[TheStranger]

Yep, 37 used to go to Napa and 48 used to take the current route.

That reminds me, of the numbers listed in my Bay Area route rundown above, 13, 25 (I think), 35, 61, 77, 82, 85, 87, 92, and 93 were all assigned after 1964, lending credence to your idea that lower numbers are more common there. 

Another place where route clustering is still common would be San Diego County, with routes 52 and 54 being both post-1964 creations as well IIRC.  But that only extends so far - numbers added after the 1964 renumbering include 163 (added in 1969), 274, 117 (now 905), and the unbuilt trio of 157, 171, and 252.

[deathtopumpkins]

Here in VA I can't for the life of me either determine a numbering system myself or find one on a website...

But it does seem that routes are clustered in certain areas (i.e. 134, 143, 152, fmr. 167, 169) all here on the Peninsula, but then you throw in oddities like 278 (runs parallel between 167 and 169) and 351 (runs parallel to 143 and then to 169), which I assume were added at a later date. And it doesn't seem like VA follows the N/S- odd, E/W- even scheme either... VA-351 is entirely almost due east-west. However, VA does number extensions of interstates with the same number (VA-164, 1-95, etc.).

[froggie]

As for my other "focus states"...

Minnesota:  Minnesota's route numbering had its original basis in the 1920 Constitutional Routes and the first crop of Legislative Routes in 1933.  Since then, due to truncations, extensions, and whatnot, Minnesota's route numbering has pretty much become arbitrary.  Steve Riner does a pretty good job of delineating the routes (and their Constitutional/Legislative Route numbers) on his Minnesota Highways site.

Mississippi:  Though additions and truncations can be a lengthy and Legislatively-involved process, Mississippi actually has a method behind its route numbering.  First off, all even numbered routes are signed east-west, with odd-numbered routes signed north-south.  This holds true even if the route in question is lined up in a different directional fashion (for example, MS 315 is more or less east-west and "North MS 315" even dips southward at one point).

Second, 1 and 2 digit routes generally increase in number from north to south and from west to east, plus there are three waves of such for both even and odd.  For example, MS 1 is in western Mississppi, increasing to MS 25 in eastern Mississippi.  Then the process begins again with MS 27 in the west and up to MS 39 in the east.  Then there's 41-63 in a generally north-to-south fashion.  For the even routes:  1-26, 30-44, then 46.  There are no MS 34, 36, 38, or 40 (presumably "reserved").  MS 50 is a post-Interstate renumbering of original MS 10.  Likewise, MS 28 is a post-Interstate renumbering of original MS 20.  MS 48 appears to be an outlier here.

Mississippi's 3 digit routes also follow mostly a clustering pattern with a couple exceptions.  MS 1xx routes are old US xx alignments that MDOT wishes to keep on the highway system....e.g. MS 145, MS 172, MS 198.  On a similar fashion, MS 245 (the only 2xx route) follows an old ALT US 45 alignment.

The remainder of the 3-digit routes are clustered.  3xx routes are in northern Mississippi, 4xx routes in central Mississippi, 5xx routes in southern Mississippi, and 6xx routes along the Mississippi Gulf Coast.  Likewise, Mississippi's "hidden routes" are also clustered:  7xx up north, 8xx in central MS, and 9xx down south.


Alabama:  I've not yet looked deep to see if there's a set pattern to Alabama's routes.  Earlier initial looks suggest there's no set pattern.  That said, there are four items of note.  First, like Mississippi, even-numbered routes are signed east-west and odd-numbered routes signed north-south.  Second, except for AL 759 (which is an extension of I-759), there are no numbers higher than 299, and no even numbers higher than 248.

Third, all U.S. routes have an underlying state route (for example, AL 7 underneath US 11), though like Tennessee these are not signed.  However, they are mileposted.  So if you see mileposts along a US route in Alabama, the mileposts are for the underlying state route and NOT for the US route (hence why US 45 has 2 sets of mileposts).

Lastly, Alabama has no qualms with keeping state highway numbers that coincide with its Interstate numbers.  So AL 10, AL 20, AL 59, AL 65...they all exist...even AL 165.

[Sykotyk]

I'm not sure what Pennsylvania does as a state, but there seem to be a few 3-digit state routes (3ds?) that are "children" of a 2-digit route, whether state or U.S.   In my area are SR 213, 413 and 513 in the vicinity of U.S. 13; and SR 132, 232, 332, and 532 that are near to SR 32.

We have our share of state routes that fit in the interstate grid, such as 581, 283 (though there is an I-283), 378 (from a former routing of I-78).

We also have a number of state routes that were old U.S. routes of the same number, such as 611, 309, 230.

Up in Mercer County you have PA-358 branching off of PA-58, as well, in Greenville.

I'm pretty sure the state tries to keep certain groups of numbers to certain areas. But, I can't remember the exact pattern (which has long since been obfuscated.

Sykotyk