Routes that were significantly modified and later restored

[Dirt Roads]

From the US Routes replaced by State Routes thread:

Not sure how much this actually gets utilized, but WV-10 and WV-80 is still a much shorter and slightly faster route between Huntington and Gilbert, West Virginia than US-52.

WV 65 between Naugatuck and Delbarton instead of US 52 through Williamson.

That's exactly what locals did if they didn't need to stop in Williamson.  When I was growing up, the part between Belo and Delbarton was WV-65 Spur.  But it was all WV-65 back in the old days. Sounds like a theme for a new thread.

WV-65 between Naugatuck and Delbarton, West Virginia has long served as a bypass for US-52 around Williamson, West Virginia.  But in the early 1950s, the routing for WV-65 switched and headed west from Belo over to Mount Gay (right next door to Logan), thus connecting Logan to points west using KY-40 at the Big Sandy crossing between Kermit and Warfield.  (The southern section became WV-65 Spur).  In the early 1980s, the portion of WV-65 from Holden to Belo was four-laned as part of Appalachian Corridor G, and extended to US-52 at Nolan (then renumbered as US-119).  Afterwards, WV-65 returned to its original routing from Naugatuck to Delbarton.

There might be some examples in this recent thread:  https://www.aaroads.com/forum/index.php?topic=30136.msg2658288#msg2658288

[hbelkins]

^^^

Which is because US 119 followed a wrong-way concurrency with US 52 out of Williamson to the Logan-Mingo county line, where it turned north on what is now numbered as WV 44.

Your mention of KY 40 brings up another example. When US 460 was extended into Kentucky, it took over KY 4 in Pike County, then followed US 23 to Paintsville, where it replaced KY 40 west to Frankfort. (Interesting note -- at one time Frankfort was served by both KY 40 (now US 460) and KY 50 (now US 421/Leestown Road).

When the new US 460 routing between Salyersville and Paintsville was built in the late 1970s, KY 40 was put back on the old route between the two towns.