The quintessential American sandwich filling is peanut butter, first marketed as a health food but soon popular among just about everybody. New Yorkers began to buy fresh roasted peanuts from street vendors in the 1870s. Because they were high in nutrients, even health experts approved of them, and homemakers sometimes chopped up a handful to make peanut sandwiches for lunch. By 1900 ten companies in the U.S.—three of them in New York City—were manufacturing peanut butter, which was considered an elegant treat to serve at teatime or an evening reception. Recipes for dainty peanut butter canapés circulated widely in cookbooks and magazines for the next several decades.
Unlike most fancy foods, however, peanut butter was cheap—20 cents per pound in the early years—and it appeared just as often on economical menus as it did in upper-class cookery. During the 1920s peanut butter became increasingly popular for children’s lunches, often mixed with cream, evaporated milk, chili sauce, or other thick liquids that made it easier to spread. When hydrogenated peanut butter became widely available a decade later, most of those combinations faded away, though the much-loved peanut butter and chili sauce sandwich held on through World War II.