Fausto Rodriguez, a Bacardi advertising executive, claimed to have been present when the drink was first poured, and produced a notarized affidavit to that effect in 1965. According to Rodriguez, this took place in August 1900, when he was a 14-year-old messenger working for a member of the U.S. Army Signal Corps in Havana. One day at a local bar, Rodriguez’s employer ordered Bacardi rum mixed with Coca-Cola. This intrigued a nearby group of American soldiers, who ordered a round for themselves, giving birth to a popular new drink. Bacardi published Rodriguez’s affidavit in a Life magazine ad in 1966. However, Rodriguez’s status as a Bacardi executive has led some commentators to doubt the veracity of his story. Another story states that the drink was first created in 1902 at Havana’s El Floridita restaurant to celebrate the anniversary of Cuban independence.

The drink became a staple in Cuba, catching on due to the pervasiveness of its ingredients. Havana was already known for its iced drinks in the 19th century, as it was one of the few warm-weather cities that had abundant stores of ice shipped down from colder regions. Bacardi and other Cuban rums also boomed after independence brought in large numbers of foreign tourists and investors, as well as new opportunities for exporting alcohol. Light rums such as Bacardi became favored for cocktails as they were considered to mix well. Coca-Cola had been a common mixer in the United States ever since it was first bottled in 1886, and it became a ubiquitous drink in many countries after it was first exported in 1900.

Rum and Coke quickly spread from Cuba to the United States. In the early 20th century the cocktail, like Coca-Cola itself, was most popular in the Southern United States. During the Prohibition era from 1922 to 1933, Coca-Cola became a favored mixer for disguising the taste of low-quality rums, as well as other liquors. In 1921 H. L. Mencken jokingly wrote of a South Carolina variant called the “jump stiddy”, which consisted of Coca-Cola mixed with denatured alcohol drained from automobile radiators. After Prohibition, rum and Coke became prevalent in the northern and western U.S. as well, and in both high-brow and low-brow circles.

Rum and Coke achieved a new level of popularity during World War II. Starting in 1940, the United States established a series of outposts in the British West Indies to defend against the German Navy. The American presence created cross-cultural demand, with American servicemen and the locals developing tastes for each other’s products. In particular, American military personnel took to Caribbean rum due to its inexpensiveness, while Coca-Cola became especially prevalent in the islands thanks to the company shipping it out with the military. Within the United States, imported rum became increasingly popular, as government quotas for industrial alcohol reduced the output of American distillers of domestic liquors.

In 1943, Lord Invader’s Calypso song “Rum and Coca-Cola” drew further attention to the drink in Trinidad. The song was an adaptation of Lionel Belasco’s 1904 composition “L’Année Passée” with new lyrics about American soldiers in Trinidad cavorting with local girls and drinking rum and Coke. Comedian Morey Amsterdam plagiarized “Rum and Coca-Cola” and licensed it to the Andrews Sisters as his own work. The Andrews Sisters’ version was a major hit in 1945 and further boosted the popularity of rum and Coke, especially in the military. Lord Invader and the owners of Belasco’s composition successfully sued Amsterdam for the song’s rights.

During the Cuban Revolution in 1959, Bacardi fled to Puerto Rico. The following year, the U.S. placed an embargo against Cuba which prohibited the importation of Cuban products, while Cuba likewise banned the importation of American products. With Cuban-made rum unavailable in the U.S. and Coca-Cola largely unavailable in Cuba, it became difficult to make a rum and Coke with its traditional ingredients in either country.