Don't forget that there are no southbound exit signs along I-79 anywhere between Morgantown and Sutton, WV, for US 19, to eliminate anyone who's looking for Corridor L (Summersville/Beckley) getting off on one of the other exits.
Those exits originally had US-19 shields on the BGS. I can still remember them being taken down after an article in the Charleston Daily Mail mentioned that several people were confused trying to use the Roanoke (WV) exit to get to Corridor L. They thought they were heading towards Roanoke (VA).
Another one in West Virginia that nobody notices (since you weren't supposed to): Exit 34 Hurricane on I-64 has never been posted for WV-34. The next exit is Exit 39 (now) Teays Valley, which is the main exit for the WV-34 shortcut over to Winfield. Locals have always surmised that this was a way that Winfield (the county seat) was trying to suppress Hurricane (which back then both were tiny little towns*). That certainly didn't work**, as the proximity to I-64 made Hurricane much larger than Winfield by 1970.
* Hurricane (pop 1,970, 1960) and Winfield (pop 318, 1960)
** Hurricane (pop 3,751, 1980) and Winfield (uhh, not big enough to make the 1980 Census)