Highways that are entirely concurrent with another highway in a state

[golden eagle]

Is I-22 completely concurrent with US 78 through Mississippi and Alabama? Or were new alignments made that deviated from the existing 78 routing?

Not sure about Alabama, but it takes on US 78's route in Mississippi.

[Bruce]

If we're allowed to jump into a time machine in this thread:

Washington's former numbering system (used until 1964) allowed for separate state highways to be co-signed with U.S. routes. For example, PSH 1 was entirely concurrent with US 99, while others had multiple state highways combined to form their routes.

[US 89]

Is I-22 completely concurrent with US 78 through Mississippi and Alabama? Or were new alignments made that deviated from the existing 78 routing?

Not sure about Alabama, but it takes on US 78's route in Mississippi.

The easternmost 10 miles of I-22 in the Birmingham area are not concurrent with US 78, which leaves the interstate for surface streets.

[Bickendan]

As mentioned at the end of Page 1: Oregon

It'd almost be easier to list the Routes that AREN'T concurrent with the Highways, such as OR 127 and 132.

[MATraveler128]

I'd say I-110 in Texas, but it turns out it splits with US 54 as short as it is.

I-126 in South Carolina is entirely concurrent with US 76.

[US 89]

I-585 with US 176 in Spartanburg, SC.

I-185 in Greenville, SC used to be entirely concurrent with US 29 before the Southern Connector toll road opened in 2001.

[roadman65]

Also surprised no one has mentioned KY's I-265 being fully concurrent with KY 841

Gonna add Arkansas's I-555 is fully concurrent with US 63

The so-called "CKC"  Chicago-Kansas City Expressway designation of IL/MO 110 is a fully concurrent designation in both states, of various other routes. IL 336 is also (currently) fully concurrent with IL 110. If IL 336 is never built Macomb to Peoria which would be a uniquely designated section, IL 336 should be deleted IMHO

Also because of the IL 110 ridiculousness, I-172 and I-88 in IL are both fully concurrent with IL 110

No longer the case for I-555. Now US 63 follows US 49 south of Jonesboro and 555 is solo to Turrell.

[bing101]

I-9 is supposed to be hidden within CA-99 if it was approved.

[mgk920]

I-4 and FL 400 (I think most, if not all Florida interstates have State Route designations, though they may not necessarily be signed)

I-41 and US-41 in Wisconsin

And Illinois - (All of I-41  is concurrent with US 41 and I-94 in the state)

I-894 (Wisconsin) (entirely concurrent with I-41 and US 41 and various parts of US 45 and I-43, totaling the entire route.)

I-80 in Indiana (Parts of I-90 and I-94 totaling the entire route in the state.)
(
Mike

[Evan_Th]

If we're allowed to jump into a time machine in this thread:

Washington's former numbering system (used until 1964) allowed for separate state highways to be co-signed with U.S. routes. For example, PSH 1 was entirely concurrent with US 99, while others had multiple state highways combined to form their routes.

Sounds like Oregon's current system, except their routes aren't signed.

[Eth]

SR 7 - entirely concurrent with US 41 or US 341

Technically no longer the case thanks to a recent rerouting of US 341 in Perry. GA 7 now exists on its own for about 3 miles (and is signed as such from I-75 exit 136).

I don't know enough Georgia highway history to know for sure, but SR 9 and SR 13 may well be former examples as they look to be old alignments of US 19 and US 23 where they aren't still concurrent.

Yep. For about 20 years from the creation of US 123 in the mid-1940s until US 23 was rerouted off of Piedmont Road to the east (first to GA 42, then later to GA 155) in the mid-1960s, GA 13 was fully concurrent with one of those US routes. And GA 9 rode entirely along US 19 until the latter was moved over to GA 400 in the early '80s.

[roadman65]

Has anyone mentioned I-26 in TN that is completely paired with US 23?