The Rum Runner was born out of inventory problems, not inspiration. Bartenders at the Holiday Isle Tiki Bar in Islamorada, in the Florida Keys, are widely credited with mixing it sometime between the 1950s and 1972 as a way to move slow-selling bottles of banana and blackberry liqueur — the two ingredients most versions still agree on. It has since become one of the most-ordered frozen drinks in the Keys, with Holiday Isle claiming the original.
Built to empty the well, not to showcase it — and it still sells better than most drinks that try.
Born from Dead Stock
The story, repeated consistently enough to be treated as the drink's real origin, is that Holiday Isle's bar staff were sitting on unsold bottles of banana liqueur and blackberry liqueur and mixed them with rum and juice to move the stock. No single bartender's name survives attached to it — the credit sits with the bar itself, and the exact year lands somewhere across two decades of Holiday Isle's history rather than one documented night.
What did survive is the drink's defining trait: it stacks more liqueurs than most tiki classics, and the deep red-purple color from the blackberry liqueur is the giveaway that you're looking at a real Rum Runner rather than a generic fruit punch.
The Spec
Two rums for a coconut-and-funk base, banana and blackberry liqueurs for the drink's signature color and sweetness, pineapple and lime for balance, and a splash of grenadine to deepen the red.
Blended is the traditional serve
Holiday Isle serves this frozen, and blending it with crushed ice is what gives the layered liqueurs a cohesive, slushy texture rather than a thin fruit punch. It works shaken over ice too, just less true to the source.
Don't skip either liqueur
It's tempting to treat the banana or blackberry liqueur as optional, but the combination — not either one alone — is what makes a Rum Runner read as itself instead of a generic tropical cooler.
Bottom Line
An inventory-clearance drink that outlived the inventory problem by seventy years — proof that "use up what's behind the bar" is a perfectly good starting point for a classic.