What states have nonduplication rule for route numbers?

[Avalanchez71]

Tennessee has duplicate routes.  All US highways also have designated state route numbers as well.  Most of US 70 is SR 1.  We have a US 19 and a SR 19. 

[SP Cook]

In WV numbers do not duplicate, with the exception of I-68 and WV 68.  WV 68 is what they renumbered the old WV 2 when they moved 2 to a multiplex with I-77 between Parkersburg and Ravenswood (this was a part of a never built idea of a four lane upgrade of the rest of WV 2).  Then Corridor E which was US 48 was renumbered as I-68.  The two roads are on the opposite sides of the state, no confusion.

[Max Rockatansky]

I suppose Florida "technically" doesn't do route duplication.  I say "technically" since all US and Interstate Highways all have a secret state designation. So while there is a FL 17 and U.S. 17 for example the latter is legislatively know by a Florida State Road number.  In this case FL 5, 35, 555 and 600 if memory serves correct.

[TheStranger]

  Likewise, US 3/MA 3 - which is mile posted as a continuous route, was also grandfathered in because, due to AASHO requirements, it was not practical to re-designate MA 3 as an extension of US 3 due to low clearances in Cambridge (Memorial Drive) and Boston (Storrow Drive), nor were there alternate roadways that met AASHO standards.

Was there ever an official plan to redesignate MA 3 south of Cambridge as part of US 3?  Interesting that height clearances would impede it being part of the US route when we had a dirt road on the US highway system as late as the 1960s.

[roadman]

Was there ever an official plan to redesignate MA 3 south of Cambridge as part of US 3?  Interesting that height clearances would impede it being part of the US route when we had a dirt road on the US highway system as late as the 1960s.

In researching old MassDPW route numbering records (which are actually fairly comprehensive) over the years, I have yet to come across any such proposal.  I suspect that part of the reason this never happened is that a short, but key, segment of both US 3 and MA 3 involve parkways under MDC/DCR control.  The MDC/DCR has traditionally been opposed to route designations on their "recreational parkways", as evidenced by the US 1 relocation off of MDC parkways in 1989.  Likewise, I recall having a conservation on this subject with a senior MassDPW highway sign engineer in the late 1980s.  He indicated that, during his tenure, which started in 1958, there had never been any proposal to change MA 3 to an extension of US 3.

[hbelkins]

Other than US/KY 79, which probably shouldn't count because KY 79 is a logical continuation of US 79 northeastward out of Russellville, Kentucky avoided duplication of route numbers up until I-69 came along. When I-24 was built, KY 24 in the northeastern part of the state was renumbered.

That's not counting US/KY 52, because US 52 does not officially enter Kentucky. The short portions of it that do cross the state line two separate times as part of Corridor G are owned and maintained by WVDOT, and are concurrent with US 119, so if necessary the route in Kentucky could officially be 119 if it became necessary.

There are separate segments of non-connected routes with the same number, however. KY 72 has two segments separated by a mountain, and KY 92 has two segments that were split when Lake Cumberland was impounded. There are other examples including streams with no crossings, and routes that dip across state lines and re-emerge.

[dvferyance]

I know Missouri did until I-64, I-72 and I-49 came in. MODOT did not renumber the state highways. Coincidentally there are exactly 3 unused 2 digit routes that could work for renumbering in MO-26, MO-88 and MO-93.

[7/8]

The only duplicate I see in Delaware is DE 9 and US 9.

[Doctor Whom]

I do wonder about states that do have duplication, such as Texas... There is both a TX-10 and an Interstate 10. I suppose in those states, you simply always prefix the highway type when speaking.

In Texas's case, two-letter prefixes are pretty much common in regular usage (US, FM, SH, IH).

Maryland does that in SHA documents such as highway location references, but people don't do that in everyday speech. The SHA goes to great lengths to inform motorists that there are an I-68 and an unrelated Md. 68, both of which have interchanges with I-70 in Washington County.

[74/171FAN]

Do you mean internally or externally? If you mean internally, then PA counts. I-283 and PA 283 have the same number, but I-283 is inventoried as PA 300. The only exception was for the brief time there was two PA 17's, prior to I-86 extended into PA. Both were inventoried as PA 17.

Not to be pedantic, but you’re confusing some terms. “PA 300” would refer to a Pennsylvania numbered traffic route (i.e. with a keystone marker) designated as 300. There is no PA 300. What you mean to say is PA 283 is inventoried as SR 300. (SR 0300, actually.) And about the section of NY 17/I-86 near Sayre, does it even show up in PennDOT route logs at all? I was under the impression that it was a NYSDOT designed, built, and maintained road that incidentally crossed the PA border for a very short distance.

I meant the 3 mile section near Erie, not the section near Sayre. This was prior to the early 2000's.

There are duplicate numbers with secret differences
There is I-283 and PA 283...PA 283 is SR 0300
There is I-380 and PA 380...PA 380 is SR 0400
There is I-86 and PA 86...PA 86 is SR 0886
There is I-99 and PA 99...PA 99 is SR 0399

BUT...there are duplicate numbers with the same inventory number.
There is US 222 and PA 222...both are SR 0222, where PA 222 is an extension of US 222 into Allentown

There are two PA 29s (SE PA and NE PA) and two PA 97s (Erie County and Adams County), and both I believe are SR 0029 and SR 0097.  The two PA 29s were once connected along and before US 309 (I think).  The Adams County PA 97 used to be US 140 and I think was match MD 97.

The Erie County PA 97 is actually SR 0197.

[lordsutch]

I do wonder about states that do have duplication, such as Texas... There is both a TX-10 and an Interstate 10. I suppose in those states, you simply always prefix the highway type when speaking.

In Texas's case, two-letter prefixes are pretty much common in regular usage (US, FM, SH, IH).

Those four (and RM) are in pretty regular use. The internal prefixes for spur, loop, park road, etc. are rarely if ever used by the public or the media. And there's an increasing number of toll routes that are numbered as if they were US or SH routes, but they don't have a state designation.

However, there is some non-duplication between categories: loop and spur numbers are never shared, nor are FM and RM (and UR) numbers, presumably because their signs are hard to distinguish at a distance.

[tdindy88]

I know Iowa, Illinois, Indiana, and Maryland have no such rule.

When the Interstates came around, though, Illinois had the decency to renumber some state routes to prevent an intersection between two routes of the same number. Indiana, not so much.

To add to this, Indiana does have a policy concerning U.S. highways and state highways (the reason SR 135 is not SR 35, due to U.S. 35's presence.) This of course never got carried over to interstates (SR 64, 65, 69, 70 and 265 technically.)

[SD Mapman]

Washington and Utah both assign route numbers by statute with all highways being State Routes regardless of system (e.g. I-5 in WA is officially State Route 5), which prevents duplication from ever occurring (similar to CA), whether or not there is a formal rule on the books.

Same with SD too.

[roadfro]

Nevada does not duplicate route numbers between systems, and hasn't since the 1976 renumbering.

During the renumbering, NDOT skipped potential state route numbers (actually FAP/FAS numbers in the Federal Aid numbering) that would otherwise be in sequence for the country clustering numbering scheme. The three known examples I can think of: SR 395 could have been a state highway in/near Lovelock, but was skipped due to US 395. SR 515 could have been a route in Carson City, but was skipped due to planned I-515. SR 580 could have been in the Vegas area, but skipped due to planned I-580.


Before the renumbering, several state highways existed that duplicated US highway numbers (6, 40, 50, 91, 93), and later interstates (15, 80). Most of these were pretty spread out and I don't think any intersected.

[Bitmapped]

Ohio does not duplicate.  There once was a SR-76 as one example.  That route is now known as SR-83.  it changed when I-80S was renamed I-76.

Not quite. There are two SR 152s over by Jefferson County. They used to be connected but haven't been since the 1940s.

[formulanone]

I suppose Florida "technically" doesn't do route duplication.  I say "technically" since all US and Interstate Highways all have a secret state designation. So while there is a FL 17 and U.S. 17 for example the latter is legislatively know by a Florida State Road number.  In this case FL 5, 35, 555 and 600 if memory serves correct.

There are State Roads 4, 10, 75, 95, 295, 375, and 595 for each Interstate of the same number, but only FL 10 is somewhat close to I-10. So there are "secret" numbers for each, but they were typically first, since many US Routes did not extend into Florida until after the post-WWII state-wide renumbering. In many cases, the SR continues after the US Route moves away onto another road alignment.

There's US 17 near FL 17, with deprecated sections labelled CR 17 (or even 17A/17B) which is probably rather confusing. US 17 is hidden FL 35 in many places, hidden FL 15 in others.

There might be some decommissioned secondary routes (795, for example) or roads like FL 1 or FL 27 which were renamed to prevent confusion.

So, I'd say that Florida only prevents number duplication if it's locally confusing. FL 27 became FL 9336* because it was close to US 27. Not sure if FL 1 / US 90 was changed to FL 10 (although FL 90 and FL 10 are used as hidden designations for US 41's "east-west" section [former US 94]).

* I've always wanted an answer to why this number was chosen, with many others available.

[hotdogPi]

Let's make a list for all states. (This is mostly from the other replies on this thread, so there may be some inaccuracies.)

AL: I-22 and AL 22.
AZ:
AR:
AK: If Interstate A1 = AK 1, there is duplication. If Interstate A1 ≠ AK 1, there is no duplication.
CO:
CA: No duplication if an extension of an Interstate as a state route is considered a single route.
CT: No duplication.
DE: US 9 and DE 9.
FL: US 17 and FL 17.
GA: I-20 and GA 20, which intersect.
HI:
IL: I-64 and IL 64.
ID: No duplication.
IN: There are duplicates, but I don't know what they are.
IA:
KS:
KY: See reply #30.
LA:
MA: I-295 and MA 295, on opposite sides of the state.
ME: I-195 and ME 195.
MI: US 24 and M-24.
MO: I-64 and MO 64.
MD: I-68 and MD 68.
MT: There are duplicates, but I don't know what they are.
MS: I-22 and MI 22.
MN:
NE: There are 2 routes numbered NE 2, not counting the user on this forum.
ND:
NC: I-74, US 74, and NC 74. The first two overlap.
NV: No duplication.
NY: I-90 and NY 90, which cross with no interchange.
NH: US 4 and NH 4, relatively close.
NM:
NJ:
OR: I-84 and OR 84.
OH: OH 152 exists twice.
OK:
PA: I-99 and PA 99. PA 97 also appears twice.
RI: No duplication.
SD: No duplication.
SC:
TX: Many, many duplicates.
TN: US 19 and TN 19.
UT: No duplication.
VA: Many 600+, also US 360 and VA 360.
VT: No duplication.
WI: I-39 and WI 39.
WY: There are duplicates, but I don't know what they are.
WV: I-68 and WV 68.
WA: No duplication.

[Max Rockatansky]

I suppose Florida "technically" doesn't do route duplication.  I say "technically" since all US and Interstate Highways all have a secret state designation. So while there is a FL 17 and U.S. 17 for example the latter is legislatively know by a Florida State Road number.  In this case FL 5, 35, 555 and 600 if memory serves correct.

There are State Roads 4, 10, 75, 95, 295, 375, and 595 for each Interstate of the same number, but only FL 10 is somewhat close to I-10. So there are "secret" numbers for each, but they were typically first, since many US Routes did not extend into Florida until after the post-WWII state-wide renumbering. In many cases, the SR continues after the US Route moves away onto another road alignment.

There's US 17 near FL 17, with deprecated sections labelled CR 17 (or even 17A/17B) which is probably rather confusing. US 17 is hidden FL 35 in many places, hidden FL 15 in others.

There might be some decommissioned secondary routes (795, for example) or roads like FL 1 or FL 27 which were renamed to prevent confusion.

So, I'd say that Florida only prevents number duplication if it's locally confusing. FL 27 became FL 9336* because it was close to US 27. Not sure if FL 1 / US 90 was changed to FL 10 (although FL 90 and FL 10 are used as hidden designations for US 41's "east-west" section [former US 94]).

* I've always wanted an answer to why this number was chosen, with many others available.

Yes, I was just saying legislatively they are all technically state roads and despite what it may say say on the shield (US or Interstate) that it's on the log book with a FL Road number.  The real interesting part is that if you look at the Florida State Highways (US and Interstates included) they actually form a grid.  The north/south odd numbers start with A1A (FL 1) and increase heading westward.  The east/west routes are even and increase southward with the multiples of 10 being considered the major ones.  So for example FL 8 is I-10 while US 90 is mostly FL 10.  The three digits usually are some kind of shorter route or doesn't head generally in an N, S, E, W cardinal direction.  The three digits (with some misplaced ones in the 100s around Miami in the 9xx grid) basically start with the first number of the major multiple of 10 they are south of.  For example; pretty much anything south of FL 50 but north of FL 60 is going to be 5XX if it is a three digit route.  For the most part even the county routes which largely were part of the state highway system at one point use the same numbering scheme or are continuations of FL state highways.  A good example of this would be FL 40 turning into CR 40 west of US 41.

But to your point yes as the routes are actually SIGNED there are obviously many duplicates given the high number of routes in the state.  Some places actually even sign the secret Florida State Route along with the US Route in the case of Martin County with US 98/FL 700 and US 441/FL 15.  The example you gave with FL 27 was changed because apparently people were getting it confused with US 27 signed nearby and ending up in Homestead instead of Miami; hence 9336 AND 997 that you see today.  A1A basically was Florida just throwing something out there to make it stand out against US 1/FL 5 and it apparently it really doesn't mean Atlantic 1 Alternate. 

For what it's worth I tend see this as probably one of the better controlled renumberings that a DOT made, in this case Florida did it in 1945...Nevada would be another good example of an orderly renumbering.  Before the routes were legislative and were numbered in order that they were enacted into law.  It's...interesting seeing some states like New Mexico and California that have massive log books like this but never went through and truly cleaned things up.  New Mexico is a complete disaster with random numbers...and California had the LRN renumberings that really fell short in terms of missing an opportunity to make signage more simple in an era we it would have been considered useful.  But...that's where I think that I said some inflaming comments in another thread...before I get too side tracked I'll stop.  One state that certainly DOESN'T have a rule with numbers duplicates is Arizona; you have AZ 89/89A and US 89/89A not to mention a US 95 then AZ 95 with the latter terminating at the former.  I'll have to check up on my New Mexico log books...there are so many that I'm honestly not sure if there is or isn't duplicates off the top of my head.

[Max Rockatansky]

Let's make a list for all states. (This is mostly from the other replies on this thread, so there may be some inaccuracies.)

AL: I-22 and AL 22.
AZ:
AR:
AK: If Interstate A1 = AK 1, there is duplication. If Interstate A1 ≠ AK 1, there is no duplication.
CO:
CA: No duplication if an extension of an Interstate as a state route is considered a single route.
CT: No duplication.
DE: US 9 and DE 9.
FL: US 17 and FL 17.
GA: I-20 and GA 20, which intersect.
HI:
IL: I-64 and IL 64.
ID: No duplication.
IN: There are duplicates, but I don't know what they are.
IA:
KS:
KY: See reply #30.
LA:
MA: I-295 and MA 295, on opposite sides of the state.
ME: I-195 and ME 195.
MI: US 24 and M-24.
MO: I-64 and MO 64.
MD: I-68 and MD 68.
MT: There are duplicates, but I don't know what they are.
MS: I-22 and MI 22.
MN:
NE: There are 2 routes numbered NE 2, not counting the user on this forum.
ND:
NC: I-74, US 74, and NC 74. The first two overlap.
NV: No duplication.
NY: I-90 and NY 90, which cross with no interchange.
NH: US 4 and NH 4, relatively close.
NM:
NJ:
OR: I-84 and OR 84.
OH: OH 152 exists twice.
OK:
PA: I-99 and PA 99. PA 97 also appears twice.
RI: No duplication.
SD: No duplication.
SC:
TX: Many, many duplicates.
TN: US 19 and TN 19.
UT: No duplication.
VA: Many 600+, also US 360 and VA 360.
VT: No duplication.
WI: I-39 and WI 39.
WY: There are duplicates, but I don't know what they are.
WV: I-68 and WV 68.
WA: No duplication.

You'll be at that for A LONG time.  BTW, you might want to review what I just said in regards to Florida, ain't as straight forward there as it seems on the surface.

[jbnati27]

One example that comes to mind in Tennessee is TN 70 and US 70. They are in fairly close proximity, one county away from each other. TN 70 is in Greeneville and US 70 passes through Newport.

[kphoger]

NE: There are 2 routes numbered NE 2, not counting the user on this forum.

Our forum member is not referring to Nebraska.  https://en.wikipedia.org/wiki/New_England_road_marking_system#Route_2

[bassoon1986]

Louisiana does not duplicate State Highways and US Highways. The exceptions are LA 371 and LA 425 which existed before US 371 and US 425 were created in the 90's. I believe LA 371 has since been deleted or changed to an LA-3xxx number.

[TheStranger]

It's...interesting seeing some states like New Mexico and California that have massive log books like this but never went through and truly cleaned things up.  New Mexico is a complete disaster with random numbers...and California had the LRN renumberings that really fell short in terms of missing an opportunity to make signage more simple in an era we it would have been considered useful.  But...that's where I think that I said some inflaming comments in another thread...before I get too side tracked I'll stop. 

With regards to California: I think the biggest flaws in how the post-1964 numbering has been handled are 1. forcing every route designation to be reviewed legislatively (when pre-1964, the signed designations were handled by the old Division of Highways) and 2. by extension, inconsistent in-the-field signage requirements if cities decide to maintain their own portions of what was a numbered route. 

One side effect of this too is a certain inflexibility in rerouting highways to reflect current traffic patterns.  For instance, the new Route 78/Route 111 bypass of Brawley is a perfect spot to clean up the 86/111 designations from there to the border, yet no changes have been made beyond a planned decommissioning of Route 86 through El Centro.  The existence of Route 14U and the past existence of Route 86S also are unintended consequences of how the California numbering system is used in practice.

[Max Rockatansky]

It's...interesting seeing some states like New Mexico and California that have massive log books like this but never went through and truly cleaned things up.  New Mexico is a complete disaster with random numbers...and California had the LRN renumberings that really fell short in terms of missing an opportunity to make signage more simple in an era we it would have been considered useful.  But...that's where I think that I said some inflaming comments in another thread...before I get too side tracked I'll stop. 

With regards to California: I think the biggest flaws in how the post-1964 numbering has been handled are 1. forcing every route designation to be reviewed legislatively (when pre-1964, the signed designations were handled by the old Division of Highways) and 2. by extension, inconsistent in-the-field signage requirements if cities decide to maintain their own portions of what was a numbered route. 

One side effect of this too is a certain inflexibility in rerouting highways to reflect current traffic patterns.  For instance, the new Route 78/Route 111 bypass of Brawley is a perfect spot to clean up the 86/111 designations from there to the border, yet no changes have been made beyond a planned decommissioning of Route 86 through El Centro.  The existence of Route 14U and the past existence of Route 86S also are unintended consequences of how the California numbering system is used in practice.

Which was the point of contention I've always had primarily with the system being handled legislatively.  You have a state with 38 million residents which makes passage of almost any law extremely difficult.  Granted I'm well aware that as a current California resident and twice passerby with two previous jobs around L.A./San Francisco a lot of my observations are from an outside perspective.  I always kind of gotten the gist that largely as the years have worn on that the legislative requirements have really ground down any will to make improvements at least from a numbering/navigation perspective.  It's just surprising that all the way back in 1964 there wasn't a bigger push to have the highway system make more sense rather than just slapping a legislative designation that matched what was being signed in the field.  Given the huge effort, why not go the extra mile like a lot of other states did?  Regardless it's still an improvement over the LRN system and I would be remiss to say that there wasn't bigger issues on the plate of legislatures...but then again, hand the numberings over to Caltrans and there might be some traction but it will likely never happen.  Makes me wonder though, why not just have something like I-238 signed as I-180 but legislatively it exists as part of route 238?  Would that technically be a duplication in the eyes of the legislatures?...I would suspect not with all ye unsigned routes throughout the state.

[PHLBOS]

US 3/MA 3 - which is mile posted as a continuous route, was also grandfathered in because, due to AASHO requirements, it was not practical to re-designate MA 3 as an extension of US 3 due to low clearances in Cambridge (Memorial Drive) and Boston (Storrow Drive), nor were there alternate roadways that met AASHO standards.

Prior to 1971, Route 3 never touched Storrow Drive and exited off Memorial Drive at the B.U. Bridge.  After crossing into Boston, Route 3 would eventually piggyback w/then-US 1 along the Riverway & Jamaicaway and then followed the current MA 203 corridor.  In hindsight & IMHO, the US/MA 3 routing should've stayed in its pre-1971 alignment; but that's another story for another thread.

I'm still sticking to the story that the reason why MA 3 wasn't US 3 is due to the DPW not wanting any odd-numbered US routes located east of US 1 (despite such occurring in other states).