US 340 originally to Winchester? 1927 Official

US 340 routed to Millwood 1929 Official

US 340 rerouted to Boyce 1933 Official

US 340 rerouted to Winchester 1936 Official

In 1936 (bridge date), US 340 was removed from SR 623 in Gaylord near the West Virginia line.
About 1950, US 340 was rerouted out of Harpers Ferry WV to cross the Shenandoah River into Loudoun County then over to cross the Potomac River into Maryland. At the bridge locations this was a replacement for bits of VA 275 and VA 275Y.

US 340 direct from WV to MD 1949 Official

US 340 clips Loudoun Co 1950 Official

Originally approved in July 1952 (AASHO) but hung up with controversy about US 340 ALT, about 1954, US 340 was rerouted at Berryville to again go south to Boyce, then continue south through Front Royal, Luray, Elkton, Waynesboro, and stuarts Draft before ending at US 11 near Greenville. This was a replacement of VA 12. The old route from Berryville to Winchester remained VA 7 (VA 7 Bus within Berryville) as well as a new US 340 ALT.
In March 1954 (CTB), US 340 was removed from SRs 667-668 west of Boyce.
In Aug 1958 (CTB), US 340 was placed on its bypass of White Post, leaving behind SR 628 and SR 658.
About 1961, US 340-522 was removed from SR 802 Ninevah.
In Feb 1969 (CTB), US 340 was approved to be placed on Page SR 615 and the US 211 Luray Bypass when constructed, with the old route through Stanley and Luray becoming US 340 Business. When the Jan 1972 CTB placed US 211 on the bypass, it made no mention of US 340. The Dec 1971 AASHO approval of US 211 Bypass-Business does not mention US 340. Oddly, US 340 Bypass is explicitly shown on the 1972 and 1973 officials.
About 1992, US 340 was finally added to Page SR 615 and US 211 to Bypass Luray leaving behind US 340 Business.
Improvements:  Upon designation, US 340 has always been paved.
The first segment of US 340 to be 4-laned was in the Cedarville area, about 1959.
In 1960-1961, US 522 was multilaned from Cedarville to Double Tollgate.
Official maps from 1961-65 erroneously show US 340 as multilaned from US 50 to Boyce (still 2-lane today).
In 1980, US 340 was multilaned from Ladd to Waynesboro.
In 1981, US 340 was multilaned from VA 7 to the WV Line.
In 1992, US 340 was multilaned from Stuarts Draft to Ladd.
US 340 was multilaned from I-66 to VA 55 Front Royal (minus one of the Shenandoah River bridges) by 1994.
US 340 was multilaned on the Shenandoah River bridge about 2010.
Posted:  Fully posted; a cutout may still be up in Front Royal, Browntown, and south of Elkton
Multiplexes:  US 250 (0.19 mi)
US 33 Bus (0.08 mi)
VA 55 (1.22 mi)
US 522, VA 55 (1.38 mi)
US 522 (8.61 mi)
Truck Route: There is a signed US 340 TRUCK route in Waynesboro, using US 250's routing to bypass central Waynesboro. This has been there back to at least the early 1990s.
Legislative names:  Stonewall Jackson Memorial Hwy, entire route (3-9-60); Lord Fairfax Highway, Clarke County (3-5-99)
Other names:  Stuarts Draft Hwy (s of Waynesboro); Rosser Ave/Main St/Delphine Ave (Waynesboro); East Side Hwy (Waynesboro to Elkton); Stuart Ave (US 33 to Page line); 3rd St/5th St (Shenandoah); Lee Hwy (US 211 duplex); Broad St (Luray); Royal Ave/14th St/Shenandoah Ave (Front Royal); Winchester Rd (Warren/Frederick Co n of Front Royal); Buckmarsh St (Berryville); Jefferson Pike (Loudoun Co)
Scenic Byway:  Page-Warren line to Front Royal (since ~2008); All of Page co except US 211 south to 340 Bus (since ~2010)
Comments:US 340 parallels the entirety of Skyline Dr on the west side. Otherwise it is a sleepy and peaceful ride through the Shenandoah Valley.
Mapmikey asks: Why isn't mainline US 340 routed onto I-64 and SR 624 Delphine Ave?