It's on your salads, your Reuben sandwiches, and almost definitely on your Big Macs. Consisting of mayonnaise, ketchup, relish, and seasonings, Thousand Island is one of the classic salad dressings, but there's a lot of confusion over who lays claim to the recipe.
The one aspect of the condiment's origin story that remains consistent throughout various tellings is that it comes from the Thousand Islands region of Upstate New York. This archipelago, actually made up of more than 1800 islands, sits in the St. Lawrence River between Canada and New York.
Food & Wine reports that the area was a popular destination for upper-class members of society in the early 20th century. One of the wealthy individuals who owned property there was George Boldt, proprietor of the historic Waldorf-Astoria Hotel in New York City.
According to one legend, Thousand Island dressing was first prepared on Boldt's yacht during a trip down the St. Lawrence River. Boldt was having a castle built on a heart-shaped island as a gift for his lover, Louisa, and the couple would regularly take trips to the Thousand Islands to check on the construction. During one voyage, the yacht's chef, Oscar Tschirky, was preparing a meal when he realized he didn't have dressing for the salad. Thinking on his feet, he mixed together what he could find in the galley—mayonnaise, ketchup, pickle relish, and Worcestershire sauce—and Thousand Island dressing was born.
There's also a second, less romantic theory explaining the dressing's inception. This story attributes the recipe to Sophia Lalonde, an innkeeper and the wife of a fishing guide in Clayton, New York, near the Thousand Islands. Sophia would make food for the tourists her husband took on fishing trips, serving her special dressing with the salads and sandwiches. Silent movie actress May Irwin reportedly tasted the condiment on a vacation to the area and liked it enough to ask for the recipe. Both legends end with Thousand Island dressing ending up on the menu of the Waldorf-Astoria—by way of George Boldt himself in the first one and by way of May Irwin passing it onto Boldt, whom she was friends with, in the latter.
The Waldorf Astoria has made many contributions to salad history. For the hotel's opening in 1893, maître d’ Oscar Tschirky—the same chef credited with concocting Thousand Island dressing on Boldt's yacht—made the first Waldorf salad by combining apple, celery, walnut, and mayonnaise.
[h/t Food & Wine]