Although tomatoes had been used in salads for decades, their combination into the ubiquitous lettuce and tomato salad first appeared in the United States in the late nineteenth century. It was popularized by Fannie Merritt Farmer’s Boston Cooking-School Cook Book. The lettuce and tomato salad did not become common until the mid-twentieth century.
Potato salad is a cold or hot side dish made with potatoes, mayonnaise, and seasonings. It became very popular in the second half of the nineteenth century and is a staple of both delicatessens and home kitchens. Hot potato salad, usually made with bacon, onion, and vinegar dressing, was associated with German immigrants and is therefore often called “German potato salad.”