History

Rickeys are a family of cocktails believed to have been created by bartender George A. Williamson in 1880 at Shoemaker's Bar in Washington DC and named after Colonel Joseph Kyle Rickey, a Democratic lobbyist who it is said Williamson witnessed squeeze lime into his whisky before topping his drink with soda. Coincidentally or not, Colonel Rickey purchased the bar in 1883 and became a major importer of limes into the US.

The Gin Rickey cocktail first appeared in print in Harry Johnson's 1900 Bartenders Manual, where he calls for "1 wine glass of Tom or Holland gin if required."

Gin Rickey
(Use a medium size glass.)
1 or 2 pieces of ice;
Squeeze the juice of 1 good-sized lime or 2 small ones;
1 wine glass of Tom or Holland gin if required;
Fill up the glass with club soda, carbonic or selters if required, and swerve with a spoon.

Harry Johnson, New & Improved Bartender's Manual, 1900

Many confuse the Rickey and the Collins. For the record, a Rickey is made with lime juice and a Collins with lemon juice. A Rickey is also usually served in a shorter glass than a Collins, but that difference is secondary.