Orphaned Interstates

[Alps]

Below: a list of every state I could find where one or more Interstates were disconnected from the "main" system - such that you can't stay within the state on the Interstate highway network. In a couple of cases, which was "main" or not was based on my judgment.

CT - 684
NY - 78
PA - 86 (at 220)
DC - 66, 95/495
GA - 59 & 24
WV - 70 & 470
KY - 24 & 69
TN - 155
IN - 275
MO - 72
TX - 44, 40 & 27
MS - 10, (22)
WI - 535
ID - 90
AZ - 15

Did I miss any? Not as good on US highways so I haven't attempted that yet. First one coming to mind is WV-US 30.

[corco]

NE- 129

And then if 40 & 27 qualify, Nevada's system is broken into two chunks too.

As far as US, US-212 in Wyoming, twice! comes to mind.

[mgk920]

Not as good on US highways so I haven't attempted that yet. First one coming to mind is WV-US 30.

(US Highways)

WI:
-US 2/141 (Florence County)

MI:
-All in Da YooPee are separate from all in the land of the trolls.

Mike

[Road Hog]

Future I-49 will cut a corner of Texas near Texarkana.

[Takumi]

I-785 will be this way in Virginia.

[vtk]

I-275 in Indiana

[on_wisconsin]

I-238 in CA 

[Bigmikelakers]

How about I-95 in DC?

[english si]

Future I-49 will cut a corner of Texas near Texarkana.

But both AR sections would connect to the AR interstate system and I-49 in TX will meet the I-69 spur.

[Roadsguy]

PA - 86 (at 220)

Is that 86 yet over there?

I wish they wouldn't kill 17. Having "New York Route 17 in Pennsylvania" is cool.

[1995hoo]

I don't know whether you're counting "Green Interstates" as part of the Interstate network. I personally would not, in which case I-585 in South Carolina qualifies for this list.

[vdeane]

PA - 86 (at 220)

Is that 86 yet over there?

I wish they wouldn't kill 17. Having "New York Route 17 in Pennsylvania" is cool.

Nope.  Shouldn't be much longer though.

[Michael in Philly]

95 in New Hampshire.
81 in West Virginia.
110 in Mississippi.

That's all I've got.

And there are plenty of U.S. routes in the West Virginia panhandles.  (I'm not attempting to do U.S. routes, but your mentioning 30 - and my first thought was, "Where's 30 in West Virginia?" - made that area jump out.  Particularly as I've crossed the state on 22.)

[texaskdog]

Are there any interstates that dont connect to any other interstate?

[agentsteel53]

Are there any interstates that dont connect to any other interstate?

apart from the H-1/H-2/H-3/H-201 aggregate, I do not believe so.

I wonder when the last time was that there was an unconnected, signed segment. 

[dfilpus]

Are there any interstates that dont connect to any other interstate?

I 73/74 in North Carolina, which only connects to Future Interstates.

[NE2]

Are there any interstates that dont connect to any other interstate?

I-585.

[hbelkins]

Did I miss any? Not as good on US highways so I haven't attempted that yet. First one coming to mind is WV-US 30.

If you're talking about intersecting other US routes, then West Virginia has several others: US 22, US 522, US 340, US 11 don't intersect other US routes within the state.

[agentsteel53]

I 73/74 in North Carolina, which only connects to Future Interstates.

I thought I-73/74 was a future interstate, still.

I had forgotten about I-585 - I still consider those "green interstates" to be part of the interstate freeway system, as opposed to the legitimate surface-road business loops and spurs (ya know, the kind with actual businesses along them!).

[1995hoo]

Are there any interstates that dont connect to any other interstate?

apart from the H-1/H-2/H-3/H-201 aggregate, I do not believe so.

I wonder when the last time was that there was an unconnected, signed segment. 

The unsigned Alaskan and Puerto Rican Interstates are also unconnected from the system.

I think I-99 probably qualifies as a recent unconnected, signed segment because it does not connect directly to another Interstate at its southern terminus–you have to use Business 220 to reach the Pennsylvania Turnpike entrance. When the road opened, its northern end didn't connect to another Interstate either. (Edited to add: I don't mean to imply it's still unconnected; I was just responding to the query about when was the last time such a segment existed.)

[cpzilliacus]

It is now decommissioned, but Maryland's I-170 would have qualified.

[dfilpus]

I 73/74 in North Carolina, which only connects to Future Interstates.

I thought I-73/74 was a future interstate, still.

I 73/74 is fully signed along US 220 from US 220 Business interchange south of Asheboro NC to US 220 Alternate interchange south of Candor NC. It is currently being upgraded north through Asheboro, where it will be extended north, but still not connected with the Interstate system. Future I 73/74 is signed along US 220 north through Asheboro to Randleman and south to US 220 Business interchange south of Ellerbe.

[vdeane]

How did the disconnected segment get signed?  My understanding from the NYSDOT site is that all 2di segments need to connect to an interstate at one end.

[Mr_Northside]

I think I-99 probably qualifies as a recent unconnected, signed segment because it does not connect directly to another Interstate at its southern terminus–you have to use Business 220 to reach the Pennsylvania Turnpike entrance. When the road opened, its northern end didn't connect to another Interstate either. (Edited to add: I don't mean to imply it's still unconnected; I was just responding to the query about when was the last time such a segment existed.)

It's debatable on how "connected" it is at the northern end at the current time as well.

[national highway 1]

I-90 in northern Idaho.
Future I-785 in VA.
The northern segment of US 395 in CA, however old US 299 did provide a connection to US 99 and the west coast.