Vintage BANK OF ST. LOUIS canvas bag......

I recently picked this canvas bag up at an outlet center. It is a vintage yellow canvas bag with BANK OF ST. LOUIS stenciled on both sides. It has old leather handles with old buckles on each end. I have picked up smaller size canvas money bags in the past, but never anything this large.

Any ideas what the purpose of this bag could have been or how old it might be?? It was just too unusual to leave behind & not bring it home.