This issue is one of the toughest surface rate cards to locate properly used anywhere, let alone Africa!
We should be thankful to missionaries throughout the world for many 'exotic' postal history artifacts left-over from all periods. A hoard of these cards turned up recently from various locations in West Africa, all originating from this 'World Bible School' return address. It's interesting that they bear departure cancels from all over the US.
This one is nice because it bears a dated African receiver from Effiakuma, Ghana - 2 Months in transit!! If you stop to think about how much mail possibly goes to an obscure destination like this, it is even less likely that anything makes it back out too!
Place mouse on image to see the reverse side of the card.