Ran across this last night...
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.vahighways.com%2Fscannex%2Froute-log%2Fimages%2Fus15-401sc.jpg&hash=3c167a2bc965ab6bd41eb959473d3fae99277108)
Even has OLD ROUTE and NEW ROUTE banners. This is today's SC 6 intersection with old US 15-301 in Santee SC.
This intersection has been a boon...at this same intersection was where I found proof US 15 and 15A were co-posted in South Carolina:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.vahighways.com%2Fscannex%2Froute-log%2Fimages%2Fus15-15a.jpg&hash=a0499942878e3b856e1b213f6a0deb5b7106e01b)