Future I-685 - Central Carolina Freeway
The infrastructure bill signed into law by President Biden in November 2021 contained, among its many provisions, text added by NC Senators Richard Burr and Thom Tillis making US 421 from I-85 in Greensboro to I-95 in Dunn a 'High Priority Corridor.' This would be the first step in asking for a Future Interstate designation along the route, or part of the route.4 The supporters of this corridor chose I-685 as its proposed number in early 2022. In its Spring 2022 meeting, AASHTO approved the Future I-685 designation, pending FHWA concurrence. FHWA concurrence was not publicized but was apparently granted in late 2022 or 2023.
PLACING OF FUTURE I-685 SIGNS IN 2024
On May 20, 2024 NC officials and members of the Carolina Core organization gathered at the newly completed bridge over US 421 (see photos below) near the Future Toyota plant in Julian and displayed Future I-685 signs that will be put up along US 421 between Greensboro. There was no announcement as to when improvement projects would start to enable the future route to become an actual interstate. Here's one of the signs displayed:5

CORRIDOR DESCRIPTION
Here's a map of the potential corridor published by the Triangle Area Rural Planning Organization (TARPO), a voluntary association of local governments in Chatham, Lee, Moore, and Orange Counties, on November 18, 2021. Notice the indecision as to whether the route should follow US 421 all the way to I-95 or head south to Fayetteville via NC 87, though an article on the May 20 sign unveiling discussing the difficulties of upgrading parts of US 421 south of Sanford seem to indicate the US 421 route to Dunn:

A later alternative map published in 2024, source currently unknown, possibly by NCDOT or a newspaper, showed 3 possible alternative corridors for I-685 south/east of Sanford:

Alternative A would follow the US 421 corridor to Dunn with portions, especially the segment linking to I-95 on a new alignment.
Alternative B would initially follow the NC 87 corridor then on a new alignment between Swann and I-295 near Spring Lake, then using I-295 to access I-95.
Alternative C would mostly follow the NC 87 corridor to I-295 near Fort Liberty (formerly Fort Bragg), then using I-295 to access I-95.
It is unknown whether any of these alternatives are 'official' or if any studies about their costs and benefits have been funded.
Alternative C would require little new road construction but would require upgrades of the existing NC 87 roadway. If I-685 is signed along a portion of I-295 it would make it the third two 3-digit interstate concurrency in North Carolina (I-785/I-840, I-587/I-795). There is only 1 other one in the rest of the country, I-680/I-271 in Cleveland.
The new overhead signage on US 421 North for the Neelley Road/Williams Church Road exit, only 1 1/4 Miles south of the I-85 Greensboro Loop exit.
The new 1/2 Mile advance sign on US 421 South, the 1 Mile advance had not be put up at this time, instead a portable VMS was used to indicate the approaching exit.
After the new 1/2 Mile advance sign there is an auxiliary sign for Toyota, presumably for the battery plant, and not a new town with that name.

There was still construction going on at the newly opened exit ramp headed south.

Approaching the Julian Airport exit on-ramp which is prior to the bridge.

A closer look at the new bridge over US 421.

A new US 421 South reassurance marker after the exit, the interstate standard shoulders continue about 1/2 mile heading south. Turning around...

The Airport Road exit ramp was still under construction headed north in July.

Looking back towards the northbound on-ramp which apparently was open.
Here's one of the official Future I-685 signs put up along US 421 in Sanford, photo by Tracy Snead:



View of new bridge being built for new exit to access Toyota Battery plant in Julian as seen from US 421 North.

Sign advertising NC Carolina Crossroads/NC Core Megasite along US 421 South prior to the new exit for the Toyota Battery plant.

US 421 South approaching the new ramp to access the Toyota Battery plant still under construction.

View of future off-ramp for new exit to access Toyota Battery seen prior to the bridge on US 421 South.

View of new interstate standard bridge being built for the Toyota Battery plant from US 421 South. The bridge was completed in May 2024.