Purists in the Florida Keys hold that a key lime pie is pale yellow, the color of its key lime juice, egg yolks and sweetened condensed milk, and that a green one has been dyed. Florida made the pie its state pie in 2006 without defining it, and a proposed fine on counterfeit pies never became law.
A key lime pie has three essential ingredients: key lime juice, egg yolks and sweetened condensed milk. In the Key West origin story told by America’s Test Kitchen, the acid of the lime juice was what “cooked” the eggs. The Christian Science Monitor described the key lime in 2000 as a yellowish fruit, smaller and rounder than the green Persian lime. WFAE’s Amy Rogers stated the rule in 2018: “Key limes are yellow, not green.” Recipes differ on baking: her no-bake pie uses only juice and condensed milk, while she notes that many recipes with eggs require baking.
For the purists, green filling marks an outsider’s pie. South Writ Large, in a 2014 essay, cited a 1977 Georgia community cookbook whose key lime pie called for green food coloring, “an additive that makes southern Floridians wince,” and wrote that authentic pie, by their account, is pale yellow. America’s Test Kitchen reported in 2024 that many Floridians believe green food coloring ruins the pie.
The legislature has been asked to police the pie before. America’s Test Kitchen reports that in the 1960s state representative Bernie Papy Jr. called for a $100 fine on anyone selling a key lime pie made without real key limes, and that the proposal went nowhere. The often-repeated year 1965 has not been confirmed in a primary record. The Jacksonville Daily Record, quoting a Museum of Florida History curator in 2006, said the pie had been debated in the legislature before and defeated, with pecan pie supporters as the usual opposition.
The 2006 law that succeeded is one sentence: “Key lime pie is designated as the official Florida state pie.” The Senate passed SB 676 by 38 to 1 in April 2006, and the governor approved it on 20 June 2006, effective 1 July. The Senate staff analysis stated that the first key lime pie was created in the 1850s in south Florida. The law defines neither color, crust nor topping.
That 1850s date is one of several. A Key West account credits fishermen and a cook known as Aunt Sally in the late 1800s. The food historian Meryle Evans told the Christian Science Monitor that the pie came out of a 1930s Borden campaign for condensed milk and that the earliest Florida recipe was in a 1939 Key West Women’s Club cookbook. Wikipedia’s survey of the printed record finds a “Tropical Lime Chiffon Pie” made with condensed milk and yolks in a Miami newspaper in 1933 and a recipe titled Key lime pie published in 1940. Sources disagree on Gail Borden’s condensed milk patent as well: South Writ Large gives 1854, Food Republic 1856.
The topping is argued alongside the color. America’s Test Kitchen notes that graham cracker crusts and whipped cream are common, while many Floridians defend a pastry crust, a meringue top or both. The Christian Science Monitor noted in 2000 that the pie is sometimes served in a pastry crust in place of graham cracker.