The cosmopolitan first appeared in 1927. Scottish bartender Harry MacElhone called a cocktail of whiskey, vermouth, Swedish punch and vodka 'cosmopolitan'. In 1934, a version much more similar to the current one was described.
In the '70s, many baristas revisited that first version of the cosmo and claimed the authorship of the current one. Among them Neal Murray, bartender at Cork & Cleaver steakhouse in Minneapolis; John Caine, bartender in Provincetown, and Cheryl Cook, bartender at The Strand restaurant in South Beach.
Cook herself said she invented the cocktail to satisfy everyone's taste. In 1985 the martini was in fashion, but women liked the glass more than the cocktail. "So I came up with the idea of creating a cocktail that would look good in this classic glass. My distributor brought me a new product and told me to create something, so I took the ingredients: Absolut Citron, a dose of triple sec, a drop of Rose's Lime and enough cranberry to make it so deliciously pink."
Dale DeGroff of the Rainbow Room at Rockefeller Center declares instead that he was inspired by a cocktail tasted at the Fog City Diner in San Francisco, and that he invented the decoration with orange peel.
The official recipe I.B.A. involves the use of lemon-flavoured vodka, but personally, I prefer to use a smooth, dry vodka, because I find it senseless to combine a flavoured product with a cocktail in which there is the freshly-squeezed juice of another fruit.
The choice between triple sec and Cointreau determines the flavour of the cocktail because although they are both orange-based liqueurs, the first has a lower alcohol content, usually between 20 and 25% vol, while the second about 40% vol. The other difference is that Cointreau has an alcohol base that comes from Brandy or Cognac, so it has a stronger flavour, which is why I choose it. The quantity of Cranberry juice would officially be 1 OZ, but to get a softer and sweeter taste you can increase it to 2 OZ.
There are several cosmopolitan recipes, one is the metropolitan, in which the triple sec / Cointreau is replaced with the creme de cassis. Another variant is the atlolitan or peach cosmopolitan, in which the triple sec / Cointreau is replaced with peach schnapps. In the 'purple rain', the triple sec / Cointreau is replaced with blue curaçao.
These are just some of the recipes of cosmopolitan variants.