The truth was that by the 1960s leftovers were becoming a joke to a lot of people, with a grumbling husband and a mystery casserole playing stock roles. That humor was a direct result of abundance. In the postwar era, a historically anomalous food economy was coming to define American culture, as the cost of food relative to income plummeted and even the poorest Americans were less desperate for calories than they had ever been. Leftovers were coming to seem less like a signal of household abundance and more like a drag. The best way to serve them, another joke went, was to somebody else.
Leftovers hadn’t been a joke to earlier generations of Americans. In the 19th century, in fact, Americans had rarely talked about leftovers as a discrete category of food at all. Cookbook authors then occasionally discussed “fragments” or “réchauffés,” but using up leftover food was so fundamental to everyday cooking and eating that most people didn’t have a special name for it. Breakfast was usually a meal of leftovers, the meat or beans or pie (or anything, really) left from the day before. Simmering stockpots were crucial catch-alls for kitchen scraps. Techniques like pickling, potting, smoking, and salting defined 19th-century cuisine because, before reliable refrigeration, cooking and food preservation were barely distinguishable tasks. Americans turned leftover milk into an array of longer-lived dairy products, and they drank whiskey and hard cider by the gallon in part because alcohol kept leftover grains and fruits edible long after they were in season. Foods that weren’t preserved had to be eaten quickly.
But by the turn of the 20th century, Americans’ relationship with leftovers was changing. Iceboxes were becoming standard features in middle-class homes, and early electric refrigerators soon followed. Refrigeration made it possible to keep highly perishable foods edible for days simply by keeping them cool, and that prompted an enormous shift in American cuisine. A whole arsenal of home preservation techniques, from cheese-making to meat-smoking to egg-pickling to ketchup-making, receded from daily use within a single generation. The unique properties of coldness as a preservative meant that the same meal could reappear in virtually the same form, day after day. It was no accident that the term “left-overs” was coined in this era, or that one of the first cookbooks devoted to them, the 1910 Left-Over Foods and How to Use Them, was commissioned by a refrigerator company.