Exit numbers with starting points that reflect aspirational/proposed highways?

[crispy93]

The NY 27 expressway on Long Island starts at Exit 57 or something like that. Someone in the New York thread explained the reasoning but I don't remember it off the top of my head.

The Southern State Parkway begins at Exit 13 because it was a continutation of the Cross Island's exit numbering. Back then, Exit 1 was at the Whitestone Bridge and increased as you went south. I have an old map that shows this

[TEG24601]

I-90 starts in Seattle at Exit 2A/B.  Because the original terminus was supposed to be US 99/SR 99 on the Alaskan Way Viaduct.

[Occidental Tourist]

CA 241 starts with exit 14 at Oso Parkway under the presumption there would be an eventual extension to I-5.  The extension was killed.

CA 91 starts with exit 6 (Harbor Fwy) even though at the time exit numbering was implemented, the westernmost 6 miles had been deleted from the books. The numbering comports with the county post mile designations.

CA 170 starts with exit 5 (Ventura Fwy) even though at the time exit numbering was implemented, the southernmost 5 miles had been deleted from the books. This is to conform with state mile post designations for this section.  The county post mile designations are even higher, still reflecting a planned end for the route at LAX.

[zachary_amaryllis]

this has been long since made correct..

but before they extended i-76 to i-70 in denver, its last exit was the junction with i-25, and was signed exit 6.

[DJ Particle]

I-90 starts in Seattle at Exit 2A/B.  Because the original terminus was supposed to be US 99/SR 99 on the Alaskan Way Viaduct.

The weird thing being that the Alaskan Way is far closer than 2 miles from I-90's start point.  Was it supposed to take over the Alaskan Way for a short distance?

[Bruce]

I-90 starts in Seattle at Exit 2A/B.  Because the original terminus was supposed to be US 99/SR 99 on the Alaskan Way Viaduct.

The weird thing being that the Alaskan Way is far closer than 2 miles from I-90's start point.  Was it supposed to take over the Alaskan Way for a short distance?

Probably not. Within a mile is Colman Dock, and 2 miles is the Spokane Street Viaduct.

[vdeane]

Where might the additional two miles have gone, then?

[sprjus4]

I-90 starts in Seattle at Exit 2A/B.  Because the original terminus was supposed to be US 99/SR 99 on the Alaskan Way Viaduct.

The weird thing being that the Alaskan Way is far closer than 2 miles from I-90's start point.  Was it supposed to take over the Alaskan Way for a short distance?

Probably not. Within a mile is Colman Dock, and 2 miles is the Spokane Street Viaduct.

I-5 to SR-99 is only 1/2 mile. Where is the additional 1.5 miles?

[rickmastfan67]

Sequential exit numbering maybe?

[wanderer2575]

Not a starting point, but based on the mile markers and exit numbers posted on its east-west freeway section in Farmington Hills and Farmington, the terminus of M-5 at Pontiac Trail in Commerce Township would be about mile 6.9, not mile 0.  Continuing north (actually slightly to the northwest) from there would put mile 0 at a junction with M-59 on the west side of Oxbow Lake.