Long US 15-15A duplex in South Carolina

[Mapmikey]

On maps from about 1936-50, US 15 in South Carolina was shown as being duplexed with a US 15A for its entire run from Walterboro to NC.  It is unclear what the point of this was (in fact a short US 15A loop existed off this routing in Lee County in the mid-40s).

Anyway, I'd seen a handful of post cards for motels or traveling pamphlets mention being on or using US 15-15A.

But I'd never seen any photos of this duplex being signed.  Until tonight...

I'm guessing not a lot of you have seen any either...

There are two postcards showing US 15-15A at SC 6 in Santee.  One is before US 301 came along and one is after...

http://picclick.com/Santee-South-Carolina-Postcard-MARION-CAF%C3%89-TOURIST-381590364093.html#&gid=1&pid=1

http://picclick.com/Unused-Pre-1980-RESTAURANT-SCENE-Santee-South-Carolina-SC-401231987178.html#&gid=1&pid=1

[The Ghostbuster]

Where were the two terminuses of former US 15A?

[Mapmikey]

For most of its existence the route ran Walterboro SC to Creedmoor NC

[noelbotevera]

Consulting US Ends, my takeaway from this is that US-15A was a temporary designation after 1935 (where the southern terminus of US 15 was in Rockingham, NC). I'm assuming that people were used to US 15's extension south to Walterboro, and eventually in 1950 US 15-A was decommissioned. The only thing that doesn't make sense is the "A". If it was meant to be an alternate route to US 15, then it was pointless.