It is generally thought that the Sour Cocktail was a direct descendant of the Punch. It may also be derived from the Royal Navy’s ration of rum that was mixed with lemon or lime juice and water. Either way, the Sour came on the scene circa the late 18th/early 19th Centuries. It was the official drink of the University of Virginia’s Jefferson Literary and Debating Society, which dates to 1825. Since Edgar Allen Poe was one of the Society’s famous members who enjoyed Whiskey Sours, the drink predates 1849, the year of Poe’s death.
While all of the above is a bit murky, we can all agree that Jerry Thomas described the Sour in his book, How to Mix Drinks; or, The Bon Vivant's Companion, in 1862. The beginning of the 20th Century then saw the birth of the Sour's many descendants. The other thing that we can agree on is that, from the Whiskey Sour to the Cosmopolitan and everything in between, Sours can be mighty tasty!