State Routes That Cross State Lines

In the hierarchy of road systems in the United States, state highways would usually be considered third, behind the Interstate Highway System and the United States Numbered Highway System.

Numbered State Highways by their definition exist within their state only. Illinois Route 53 is a completely different route than Indiana Route 53, for example. Occasionally, a number from one state will continue onto another state highway, a great example of this would be Route 200, which begins as Idaho Route 200, becomes Montana Route 200, which becomes North Dakota Route 200, and finally Minnesota Route 200. Each of these routes exist within its home state highway network.

But in unusual circumstances, a state highway as part of its own highway network, can cut into another state briefly, and these are the highways we're going to talk about today.

Route 17, known throughout much of the state as the Southern Tier Expressway, is the much earlier number for the road that is slowly being converted into the eastern Interstate 86 (why the western I-86 exists is beyond me).

As part of this alignment, it enters the State of Pennsylvania for about one mile near South Waverly, PA. This alignment is the result of an abandoned Delaware Lackawanna & Western railroad right of way that was abandoned and converted into the freeway. The right of way dipped into Pennsylvania, and thus the road did the same along a similar alignment.

2006 Photo of NY-17 at the NY/PA State Line by Daniel Case, Wikipedia Commons

From TrainWeb, "Here is the DL&W station. Even though the photo says "Waverly NY" it was actually located in S. Waverly PA. This shot is looking East down the DL&W main. Fulton St. is crossing the tracks right in the foreground of this photo. 

Today the Route 17 bridge crosses over Fulton St at this spot."

2) Maine Route 113

Maine State Route 113 runs for 54 miles in the far western part of the state. Despite being a Maine state route, it actually briefly enters the State of New Hampshire on more than one occasion.

While it is uncommon for a state highway to enter a different state, an earlier routing of ME-113 creates an even more unique station.

ME-113 has a loop, which is an earlier alignment of the route near Stow, ME, known as 113B. Interestingly, the majority of this loop is located in New Hampshire, and thus is numbered NH-113B, making it an extremely rare occurrence of a suffixed state route taking a number from another state, as it has no relation to NH-113, which, to add further confusion, is only about 11 miles south of Stow in Conway, NH.

To further confuse things, NH-113B also enters Maine. About a mile of the alignment is within the State of Maine, who does not consider it part of their state highway system, classifying it as an unnumbered town-way. Maintenance along the route is the responsibility of NHDOT.

Image: NH-113B by Doug Kerr, Wikipedia Commons

Owing to their small size and the fact that the New England area had their own road marking system that predated US Highways, there exists quite a few examples of highways crossing state lines in that region. Another of these routes is NH-153, which crosses into Maine for about 1.9 miles near Province Lake, which was obviously easier to build around than over, hence why this road crosses the state line.

Much like NH-113B, the road is the complete responsibility of NHDOT, however the road is marked with Maine style highway signs within the state, in spite of not being a Maine state highway.

Image: Maine Style 153 sign, Doug Kerr, Wikipedia Commons.

4) Minnesota Route 23

Now we travel to the Midwest to discuss another state highway that crosses into another state as the result of complex geography. MN-23 sort of cuts the state of Minnesota in half diagonally, as it begins in the southwestern part of the state, ending at Interstate 35 near Duluth, for a distance of about 343 miles. 

Immediately south of Duluth, the highway crosses the St. Louis River via a bridge located in the State of Wisconsin, meaning MN-23 enters Wisconsin for about half a mile in length.

Minnesota 23 in Wisconsin. Google Maps.

No indication is given on the road showing state lines were crossed, and MNDOT maintains the entire road, even in spite of the road crossing into Wisconsin.

5) Arkansas Route 43/Oklahoma Route 20

This is probably the most complicated example of a state highway entering another state in the entire US, but it really doesn't have to be. Let's start with Route 43, which starts in Missouri as MO-43. Missouri 43 ends at the State of Arkansas, where it becomes AR-43, but this only lasts for a few hundred feet before the road goes into Oklahoma, as this is where Missouri, Arkansas and Oklahoma all meet.

Google Maps view showing OK-20 and AR/MO-43. If OK-20 ended at AR-43 as opposed to MO-43, this would be far less confusing.

Arkansas 43 continues for about 5 miles where it is either located wholly in Oklahoma, or directly over the border with Oklahoma. When it meets OK-20 at a junction, it definitely enters Arkansas, and continues south within that state or hugs the border once again. Now why there's three segments of the road in the state, I can't answer that.

What makes this even more complicated is Oklahoma Route 20, which for some reason instead of ending at AR-43, gets multiplexed with AR-43 north to the Missouri State Line, thus briefly entering Arkansas itself along the same road. So Oklahoma Route 20 ends at the Missouri/Arkansas Border. Go figure.

OK-20 and AR-43 are probably the only instance of two different states' highways being multiplexed along the same road.
I have no idea where I'm going, especially since that's a Missouri highway sign heading south. Image: The Road Less Taken

I don't know if these are the only five examples of state highways entering another state in the US, but they are certainly a unique occurrence, as state DOT's would clearly prefer their roads to exist wholly within their own states. Still, geography, right of way acquisition, and whatever is going on with the MO-AR-OK border sometimes make roads cross state lines. 

Thanks as always for reading, and let me know if there are any other examples of state highways existing in other states!


  1. The state line between New Mexico and Texas follows the 19th Century path of the Rio Grande between El Paso and Anthony, where the boundary then turns east. The river channel has moved significantly since then, but the boundary stayed the same. NM-28 runs between Las Cruces and the Texas line north of El Paso, where it becomes FM 259. There is a short stretch north of its southern terminus where it briefly reenters Texas, maybe a 1000 ft. segment. I've driven on it, and don't remember any signage marking the state line crossings. I have to assume New Mexico maintains this piece of road. There are no street intersections along there.

  2. The only other example I know of is the state route (s) 54 that share pavement in Maryland and Delaware


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