Specific Roadgeekery ONLY Seen In 2 Adjacent States

[thenetwork]

Here is a challenge to you roadgeeks:

Name something highway-specific that can be found in ONLY 2 NEIGHBORING states, but NOT in their other neighboring states.

Here are two to start:

1) State routes that are square and feature the state name are found in Illinois and Indiana (their other border states use different shape markers with no state name).

2) Horizontal overhead traffic signals are the norm in both New Mexico and Texas (other neighboring states are traditionally vertically-mounted signals).


Others?

[hotdogPi]

NH and ME: Speed limits above 65 (or above 110 kph if including Canada)

[bassoon1986]

Green state highway shields in LA and MS (historically).


iPhone

[hbelkins]

Circle state route markers in Delaware and New Jersey. (Yes, I know other states use them, including my own, but I know of no other adjacent state pairs that use them.)

[roadfro]

California & Nevada:

• "Freeway Entrance" sign packages
  
• White county-based milepost/postmile signs on state-maintained highways (although Nevada is now installing enhanced versions of these similar to MUTCD enhanced reference location panels, the original small ones are still installed at structures, along interstates at integer mileages, and in some urban settings)

[plain]

Tolls can be found in NY, MA, and RI, but not CT (though it used to be).

Underwater vehicular tunnels can be found in NY and MA, but not CT. Same with MD and VA, but not WV.

FYA's can be found in VA and KY, but not WV.

[Pink Jazz]

VA and NC - Exit tabs on a separate panel, instead integrated into the BGS.

[US 89]

California & Nevada:

• "Freeway Entrance" sign packages
  

These are pretty common in neighboring Utah as well.

[cl94]

3X4 reference markers in New York and Vermont. No other states mark mileage on state-maintained roads with reference markers, though a few use a similar postmile system.

[hotdogPi]

3X4 reference markers in New York and Vermont. No other states mark mileage on state-maintained roads with reference markers, though a few use a similar postmile system.

NH has a few. Very few, though, and they haven't been deciphered yet.

[roadfro]

California & Nevada:

• "Freeway Entrance" sign packages
  

These are pretty common in neighboring Utah as well.

Do they use the full package, like this example, with "Freeway Entrance" sign, direction banner, route shield, and arrow?

I didn't recall any from previous Utah visits, and I poked around briefly in Street View and didn't see any. I've seen some uses of just the "Freeway Entrance" sign, but not with the route shields in the whole package that is standard in California and Nevada.

[US 89]

California & Nevada:

• "Freeway Entrance" sign packages
  

These are pretty common in neighboring Utah as well.

Do they use the full package, like this example, with "Freeway Entrance" sign, direction banner, route shield, and arrow?

I didn't recall any from previous Utah visits, and I poked around briefly in Street View and didn't see any. I've seen some uses of just the "Freeway Entrance" sign, but not with the route shields in the whole package that is standard in California and Nevada.

Ah, not the full package. Misread that. The standalone Freeway Entrance sign is used at the majority of entrance ramps, though.

[Roadgeekteen]

Arizona and New Mexico: Complete lack of 3dis.

[xonhulu]

California & Nevada:

• "Freeway Entrance" sign packages
  

These are pretty common in neighboring Utah as well.

Do they use the full package, like this example, with "Freeway Entrance" sign, direction banner, route shield, and arrow?

I didn't recall any from previous Utah visits, and I poked around briefly in Street View and didn't see any. I've seen some uses of just the "Freeway Entrance" sign, but not with the route shields in the whole package that is standard in California and Nevada.

Oregon has recently put a few of these in, and they are the "full package."  Here's an example from Kuebler Blvd at I-5 in Salem.

But if you throw "with state-named shields" into your specifics, your example still works!

[mrcmc888]

New York and Pennsylvania- A directional letter suffixed US route that runs alongside its parent (6N and 9W)

Arkansas and Tennessee- 1 interstate and 4 US routes crossing a state line in a concurrency

[Ben114]

Massachusetts and Rhode Island: sign errors

[interstate73]

New York and Pennsylvania- A directional letter suffixed US route that runs alongside its parent (6N and 9W)

Arkansas and Tennessee- 1 interstate and 4 US routes crossing a state line in a concurrency

9W continues down the Hudson into New Jersey as well! Terminates in Fort Lee just shy of the GW Bridge.

[Scott5114]

3X4 reference markers in New York and Vermont. No other states mark mileage on state-maintained roads with reference markers, though a few use a similar postmile system.

Oklahoma uses references markers, although they are posted in different places, and the numbers on them convey different things than the New York standard.

[tdindy88]

Indiana and Ohio both feature the same style of county-line signs along their non-freeway highways, with the name of both the county you're entering and the one you're leaving.

[TheOneKEA]

MD and DE share a state highway (54) that forms the border between the two states for a short distance.

[Ned Weasel]

I was about to mention Texas and Arkansas having discontinuous segments of Interstate routes (69 and 49 respectively), but then I realized WB I-220 in Louisiana is signed as "TO I-49" and I-220 is not officially part of I-49.  Why I-49 needs to be routed straight through Shreveport instead of sticking to the beltway is beyond me.

[Fictional Highways]Maybe this will become the next Somerset freeway that goes unbuilt for so long people that people will eventually realize the 2DI designation would be served just fine without building it and by doing a simple renumbering, except in this case, all the ramps are already there, so all you need to do is change the signs.[/Fictional Highways]

Mississippi only has one segment of I-69, I can't even find signs for I-69 in Tennessee, and I'm not sure whether that stub end of the Purchase Parkway at the Kentucky border even counts, so that's why I thought this almost fit the category.

[hbelkins]

Mississippi only has one segment of I-69, I can't even find signs for I-69 in Tennessee, and I'm not sure whether that stub end of the Purchase Parkway at the Kentucky border even counts, so that's why I thought this almost fit the category.

It doesn't. I-69 officially ends at the US 45 bypass interchange; the route continues as the Purchase Parkway only.

[webny99]

3X4 reference markers in New York and Vermont. No other states mark mileage on state-maintained roads with reference markers, though a few use a similar postmile system.

Oklahoma uses references markers, although they are posted in different places, and the numbers on them convey different things than the New York standard.

Also, Oklahoma doesn't border NY/VT. 

[jmacswimmer]

Maryland, and to a lesser extent Delaware & Virginia, use this "LANE ENDS" sign that I don't think I've seen in any other states.

Delaware also seems to have copied the Maryland-style exit tab ("EXIT" far left, ## far right, and huge space between) on a couple newer sign installs on the Delaware Turnpike portion of I-95.

[index]

NC and VA seem to have an aspect of some small towns where they are built around a railroad track with the street grid. (Ashland, VA and Waxhaw, NC being tow examples of this) Two main streets on both sides of the track and the front of all the buildings faces the tracks. I haven't seen this in many other places. It seems to be very limited to NC.