States with a majority of interstates renumbered?

[ilpt4u]

A "maybe"  for Illinois (and Missouri) would be I-70 taken off the PSB and the first mile or two in E St Louis and St Louis, and moved onto the new(er) construction Stan Musial Bridge and its approaches on both sides of the Mississippi

Not sure if that fits the theme of this thread, as that PSB did carry and still carries I-55/I-64/US 40 - just lost I-70

Also in Missouri, I-44 was extended a few miles north, duplexed with I-55 then along former I-70 to meet I-70 where 70 now joins the Mark Twain Expressway, as a result of I-70 moving from the PSB to the Stan Span. Makes the fun effect of I-44 East continuing as I-70 West at route termination. I believe I-44 East even has a Control of Kansas City in Downtown STL

So slightly more for MO than just the 1 mentioned up-thread:

With the 2 states I'm familiar with, it's almost the same numbers as day one, but there's still 1 in each...
...MO: The first 20 miles of I-270 was first designated as I-244. MoDot wanted 144 for it first, but got changed to an even first digit because of its partial beltway status.

[Avalanchez71]

Tennessee had I-181 renumbered to I-26 and I-265 renumbered to a rerouted I-65.

Wasn't there also a portion of I-240 in Memphis that was I-255?


iPhone

Yes that is correct.

[mrsman]

A "maybe"  for Illinois (and Missouri) would be I-70 taken off the PSB and the first mile or two in E St Louis and St Louis, and moved onto the new(er) construction Stan Musial Bridge and its approaches on both sides of the Mississippi

Not sure if that fits the theme of this thread, as that PSB did carry and still carries I-55/I-64/US 40 - just lost I-70

Also in Missouri, I-44 was extended a few miles north, duplexed with I-55 then along former I-70 to meet I-70 where 70 now joins the Mark Twain Expressway, as a result of I-70 moving from the PSB to the Stan Span. Makes the fun effect of I-44 East continuing as I-70 West at route termination. I believe I-44 East even has a Control of Kansas City in Downtown STL

So slightly more for MO than just the 1 mentioned up-thread:

With the 2 states I'm familiar with, it's almost the same numbers as day one, but there's still 1 in each...
...MO: The first 20 miles of I-270 was first designated as I-244. MoDot wanted 144 for it first, but got changed to an even first digit because of its partial beltway status.

The I-44 example is a really good case for the proposition that just because a route changes number, doesn't mean that the route needs to change its control city.  So while it may seem weird that from St Louis you will go on an eastbound route to head to Kansas City, that expressway running by the Gateway Arch was once I-70 West and will still lead you to I-70 West, so Kansas City is more than appropriate.  (Even if you have to think a minute about it.)

Another good example of that is I-40 west to Los Angeles.  I-40 doesn't go to Los Angeles, but it is a replacement for US 66 which once did.  And if you follow I-40 west, you will eventually be led to I-15 to I-10 toward Los Angeles.

[mrsman]

Yes, comparatively, the interstate highway system is young enough that decommissioning former interstate routes is very unusual.  I am fascinated with Business I-80 through Sacramento for this same reason.   Freeways are expensive to build, so re-routing another freeway or abandoning a freeway can be very costly. 

With Business I-80 in Sacramento, the only portions of it that were built as I-80 (as opposed to originally US 40 or US 99W/US 99E) are the Pioneer Bridge, WX Freeway, and part of the midtown north-south section between 29th/30th Streets.  The rest predated the Interstate system and is to some extent why CalTrans had hoped to build a new alignment along the railroad tracks in North Sacramento prior to the 1979 local vote that shifted funding for that to light rail.

There aren't that many freeways in California that are "former Interstate" and no longer in the system, beyond the following:

- Santa Ana Freeway/US 101 between I-5 and I-10, was I-105 for a couple of years in the 1960s but never signed.  the San Bernardino Freeway segment between US 101 and I-10 was I-110 but never signed, not sure if that counts as it is signed as I-10.

- Former US 395/I-15 through Miramar MCAS, bypassed by the current I-15.

- Former I-80 along the Central Freeway, not sure if ever fully signed on it though.  Partially US 101 and partially now essentially an unnumbered route to Octavia Boulevard.

- Business 80/US 50, depending on how one counts the unsigned I-305 segment.

- Would Route 99 being Temporary I-5 between Sacramento and Stockton in the 1970s count?

- Not sure if I-280 was ever signed on the portion of Route 1 between current I-280 in Daly City and Font Boulevard in SF.

Slightly fictional, but IMO, singing I-80 along the stub to Octavia would be a good idea.  It is somewahat unsettling having a freeway maintained by Caltrans that doesn't have a signed number.  Its not  US 101, because US 101 exits at Van Ness, so this little stub needs a number too and I-80 would fit given the history involved.

[US20IL64]

Well the obvious ones in Illinois were where state or US highways became interstates.
I-88 Reagan Tollway was IL 5 E-W Tollway and before that was IL 190 and before that was US Toll 30.
I-290 Eisenhower Expy was at one point I-90 until 1978 when 90 got rerouted onto the Kennedy Expy and Northwest Tollway.
I-90 Addams (NW) Tollway was IL 194 until 1978.
I-190 was IL 594.
I-39 was added to US 51 and I-90.
I-72 was added to US 36 in the 1990s.
I-172 was IL 336 until the 1990s.

Before called IL-594, O'Hare access road was IL-194, which started from Edens jct. And it's really western end of JFK X-way.
Changed in 1971, when 90 extension was completed to Schaumburg. Before that, NW Tollway [Addams] was signed as "To 90". Shown on old maps.

Late 1978 was the 90 to 290 and 194 to 90 changes. 290 is a loop to and from 90, and shouldn't be part of i-88.

At one time, the Skyway was co-signed "Toll Business US 12-20".