Interstates that changed the most from planning stage to building stage

[ilpt4u]

Wasn't I-24 planned to run up Vincennes, IN then across to Saint Louis?

Vincennes to STL was part of the original I-64 routing, which would have followed US 50 in IL and US 150 in IN for the STL-Louisville route. This is why parts of the route, especially around Vincennes, are freeways, as it was early 64 construction before the reroute

[Bickendan]

There were plans for 80N, now I-84(W) to eventually reach the Oregon Coast.

As far as I can tell, 80N was never intended to reach the coast. It was intended to use the non-built Mt Hood Freeway between the Marquam Bridge (I-5) and I-205, but was shifted onto the Banfield (US 30) instead.
Unbuilt I-505, however, was proposed to follow St Helens Road and along US 30 from I-405 to Clatskanie, with the only portion ever constructed was the stub freeway to Nicolai St (which itself was a realignment off the Thurman and Vaughn St proposal). Plans were drafted for a freeway facility to the St Johns Bridge (US 30Y) as a Phase 1 before the freeway revolts killed the Mt Hood, then I-505 and I-305 in Salem (repurposed into the Salem Parkway/OR 99EB)

[CapeCodder]

I remember there were several alignments proposed for 24 but not sure if the routings.
I am sure all those were West of 57. The idea of East through Carbondale was later like 1965 with the Supplemental Freeway system.
There have been multiple corridors proposed and studied there. A 4lane expressway between Murpheysboro and Pickneyville lives on.

I saw what is now I-155 labeled as I-24W on an old map once.

[MikieTimT]

I-69, the never to be completely built road.

Planning, building, planning, building, planning, building...

[OCGuy81]

I-69, the never to be completely built road.

Planning, building, planning, building, planning, building...

That's what I was going to say as well.

[roadman65]

Could you count I-89, given its original plan was to parallel US 7?

I don't want to pick on SectorZ here; just quoting to ask: if anyone has official docs on this, I'd love to see a copy. It's one of those things that I'd like to be true, but I can't make that call until I've seen some sources.

The closest I've seen to this are:
* VT wanted I-91 to run in the US 7 corridor instead of US 5 (there are more prominent cities there)
* there was a three-state interstate plan for US 7 that would have connected to I-89 (but didn't mention an interstate number for it)

I've heard that about the US-7 corridor for I-91 as well. A few parts of that proposed corridor exist, but I believe only as bypasses of certain towns

I believe that is why CT built the US 7 partial freeway in Danbury and the one north to New Milford as well,

[DJStephens]

Could you count I-89, given its original plan was to parallel US 7?

The closest I've seen to this are:
* VT wanted I-91 to run in the US 7 corridor instead of US 5 (there are more prominent cities there) there was a three-state interstate plan for US 7 that would have connected to I-89 (but didn't mention an interstate number for it)

I've heard that about the US-7 corridor for I-91 as well. A few parts of that proposed corridor exist, but I believe only as bypasses of certain towns

I believe that is why CT built the US 7 partial freeway in Danbury and the one north to New Milford as well,

So if 91 followed US-7, for it's entire path, where was 89 programmed?  Same as today?  Meaning a Boston - Montreal route??  Ending at Burlington?  There are pieces of Super Two near Bennington, to best of belief.  Don't know if space is reserved for an additional carriageway.   Never been on that piece of US - 7.