By the late 19th century, as salads became ever more popular, restaurants began to include them on menus in numbers and presentations—many of them European in origin—previously unimagined. In The Epicurean, a cookbook published in 1894, Charles Randhofer, the chef at New York's Delmonico restaurant, lists more than 60 kinds of salad, divided into categories that include green salads, cooked-vegetable salads, raw-vegetable salads, and cooked salads, among which are many with seafood or meat, precursors to the chicken, egg, and tuna salads still beloved today.

The years around the turn of the century witnessed a fascination with progress in the domestic sphere in America. For one thing, the introduction in the late 19th century of the cast-iron stove—in my view one of the earliest and greatest facilitators of women's liberation—replaced the grueling and time-consuming job of open-hearth cooking, granting women the freedom to experiment with more-nuanced cuisine. The serving of salads eventually became a sign of refined tastes, favored by the upper and upper-middle classes.

As the middle decades of the 20th century approached, the increasing availability of canned, jarred, and frozen foods gave rise to lively and sometimes weird concoctions. Molded salads, popular since the introduction of powdered gelatin in the late 19th century, took on all sorts of new guises (one of my favorites is a well-seasoned—often with celery salt—tomato ring filled with seafood or even chopped hard-cooked egg). Some ingredients became, for a time, a salad maker's best friend: decent mayonnaise, chili sauce (of the mild and nonthreatening variety), roasted peppers, anchovy paste, and corn niblets were just a few of the items readily available for enlivening a salad. Some of these ingredients—canned chickpeas, for example, and kidney beans—are still popular salad staples today. Others, like canned string beans, have largely fallen out of favor.

Canned fruit, in particular, spawned some of the oddest dishes. A 1941 church fund-raising cookbook from Ridgewood, New Jersey, gives a recipe for "Delicious Salad", containing a can each of pineapple and sweet cherries along with sliced oranges, marshmallows, and a cooked dressing of eggs, vinegar, and sugar with beaten cream folded in at the end. In case there might be confusion that this could be construed as a dessert, the recipe suggests serving it atop crisp lettuce. In my childhood, I was on more than one happy occasion offered canned peaches stuffed with cream cheese and napped with vinaigrette.

When it came to dressings during the early and mid-20th century, what we now consider basic materials, such as olive oil and good-quality vinegars, were virtually unknown in most American kitchens. (In many parts of the country, olive oil could be purchased only in minuscule amounts at pharmacies, where it was—and indeed occasionally still is—sold as a laxative and skin ointment.) Thus were born our seemingly numberless types of dressing, many, such as thousand island, based on ingredients near and dear to our hearts (and our refrigerators), like mayonnaise and pickles (see All Dressed Up for a closer look at a few of our favorite dressings).

High-end restaurants, country clubs, and hotels sometimes had access to a greater selection of ingredients during these years. They also employed chefs with classical training who had an idea of what could acceptably be combined. Their customers tended to fare better than people at home, who depended on the popular cookbooks of the time. Some of the brightest creations of the era were main-course luncheon salads, designed to appeal to ladies: the chef's salad (lettuce, ham, beef tongue, turkey or chicken, and hard-cooked egg) served at the Ritz-Carlton Hotel in New York City, the mixed-greens salad with green goddess dressing at San Francisco's Palace Hotel, and the cobb salad (lettuce, tomatoes, bacon, chicken, hard-cooked egg, avocado, and roquefort) at the Brown Derby in Los Angeles were all lasting successes.

The grand experiment continues. In recent years, the choice of salads, as both first and main courses, and the list of ingredients have grown exponentially, taking cues from around the world. As the foods at our disposal become more varied and diverse, salad, by its very nature, becomes the ideal playground for new ideas. The salads we eat today reflect more vibrantly, and more faithfully, than ever before the many immigrant cultures that thrive within our borders and also our burgeoning appreciation of small farmers and locally sourced products.

Whereas just a decade or two ago supermarket produce aisles offered a virtually unchanging cast of bare basics, today's food stores and farm stands are bursting with unprecedented variety. Even familiar salad vegetables now appear in numerous incarnations—heirloom tomatoes of every size and color, purple carrots, cucumbers both great and small. We have red onions, white onions, yellow onions, vidalia onions, walla walla sweet onions, not to mention spring onions, scallions, shallots, and a whole range of chives. Garlic, once considered too aggressive for a gentleperson's table, is now ubiquitous in our salads. The selection of greens one can buy today is also staggering: formerly obscure finds, including such chicories as radicchio, chioggia, and the long, serrated puntarelle of winter, are no longer uncommon. Many kinds of cress and fresh herbs can now easily be bought year-round. And almost any market sells bags of washed mixed greens under the name mesclun. Contributing to this diverse tableau are once exotic vegetables like bean sprouts and mizuna and tatsoi (a cousin to bok choy) greens.

Americans are exhibiting the same, voracious curiosity when it comes to what they put on their salads. The array of oils and vinegars at specialty stores today is nearly overwhelming. High-quality first-pressing extra- virgin olive oil, from all over the world, is a given, and the vinegars on offer are made from an astounding diversity of fruits, wines, and even grains. Many of us are dispensing altogether with crystallized salt for boosting our salads in favor of using soy sauce. Indeed, the introduction of that and other Asian condiments such as mirin, sesame oil, rice wine vinegar, and ginger has vastly enhanced the everyday salads of countless home cooks and restaurateurs—a reflection, perhaps, of the gifts that America's Asian immigrants have bestowed on our everyday larder.

And yet, many of the hearty favorites of a simpler time are still with us: hard-cooked eggs, potatoes, corn, shrimp, chicken, turkey, ham, celery, canned tuna, and good old cabbage and romaine. As new gets added to old, there would seem to be no limit to the capacity of our cupboards, refrigerators, and gardens. American salad, it seems, makes room for all comers while remaining, in some elemental way, our own.