Notes:

The inaugural Whiskey Sour recipe emerged in 1826 and quickly captured the hearts of many, considering the era's limited avenues for instant fame. Its charm lay in the lemon juice's ability to mellow the robust, woody edge of the whiskey without entirely obscuring its character, thus transforming a spirit that some found off-putting into a fascinating libation.

Original recipes leaned heavily on water and were conservative with the lemon. However, it didn't take long for bartenders to push the lemon to the forefront, doing away with water. Over time, the recipe saw numerous adaptations, like Jerry Thomas' 1887 rendition featuring a Curacao float.

By 1885, a distinctive variant appeared, crowned with a red wine float. Although it has been dubbed the Southern Sour and the Continental Sour, it's predominantly recognized as the New York Sour. Intriguingly, this beverage, first published in Boston and allegedly conceived in Chicago, was named after New York. A Chicagoan bartender once crafted a "pleasant-looking, red-headed" Whiskey Sour, and he explained to a journalist that the claret (red wine) enhanced the drink's appearance and flavor profile. Despite its recent revival, the New York Sour doesn't quite have the same visual allure, primarily due to adding egg-white foam and serving the cocktail over ice.

The inclusion of egg white foam for texture and aesthetic appeal wasn't introduced until the 1920s. This addition is now deemed a crucial element of the Whiskey Sour in many cocktail circles today.