The first thing one needs to know about the history of pizza is that there’s no such thing as the official history of pizza. At several points during our conversation, Carol Helstosky, author of Pizza: A Global History and Associate Professor of History at the University of Denver, pauses to make sure I know that several key junctures in pizza’s development are hotly contested among die-hard pizza fans. Because as anyone who has spent any amount of time scrolling through Tumblr or Instagram accounts knows—there’s no food that captures our zeitgeist quite like ‘za.

From how pizza margherita got its name, to the definition of pizza itself, there’s plenty that remains up for debate in spite of its overwhelming popularity. Depending on what counts as “pizza,” for example, its origins can date all the way back to ancient Greece, or up to just a few centuries ago. But to write her book, Helstosky had to start somewhere. She now considers any “flatbread made with yeast, baked at a very high temperature, and topped with tomatoes and cheese” to be pizza, a standard that fast-forwards through centuries’ worth of portable, bread-based meals and puts the start date of pizza as we know it firmly in 18th-century Naples.

There, pizza started as “a quick, nourishing, and cheap meal” for the working class, a tradition that lives on in the form of dollar-slice joints. And though it remained a particularly Neapolitan dish for more than a century after its invention, it eventually followed the now well-worn path of ethnic food in America: introduction by immigrants, increasing popularity outside the Italian-American community, and eventually assimilation into the mass market.

Along the way, however, the history of pizza has found itself affiliated with royalty, World War II, and the most important demographic at all: hungry college students. Without further ado, here are the five phases that shaped pizza as we know it.

Illustrations by Max Schieble

A Humble Snack from Naples

For the soldiers, sailors, and other blue-collar laborers who were pizza’s earliest enthusiasts, options were limited. In 1700s Naples, Helstosky says, pizza came in two basic varieties: “You have the marinara, which was tomatoes with some anchovies and perhaps some oregano on it; you then might have something sort of like a pizza bianca, with garlic and seasoning.” That was it. Then again, that’s all workers really needed from early pizzerias, which mostly served to provide efficient, inexpensive fuel for customers. Pizza wouldn’t acquire any gourmet cachet for a while.

Pizza remained a local Neapolitan specialty for over 200 years, to the point where “if you lived in Venice, for example, you wouldn’t know anything about pizza unless you had traveled to Naples and tried it.” Before it made its way to the United States or the rest of Italy, however, pizza evolved into something closer to what we eat today, with mozzarella, sauce, and basil-topped margherita developing sometime in the 19th century.

There’s plenty of “mythmaking and patriotic folklore” surrounding how the margherita got its name, and Helstosky offers just one example. According to this particular urban legend, Margherita of Savoy, then the Queen of Italy, wanted to sample the local specialty on a trip to Naples; of the three pies she was served, the margherita was the one she liked best, and it was subsequently named after her. That’s just one story, among many, though.

By Italians, For Italians

Like many “ethnic” foods now available in your local supermarket’s frozen foods section, pizza came to America during the massive influx of southern- and eastern-European immigrants, beginning in the late 19th century. (See: bagel.) Since most Italian immigrants were coming from the southern half of the country, Neapolitan foods like pizza ended up crossing the Atlantic before they even traveled up the boot. “As odd as it sounds,” Helstosky says, “you were more likely to find pizza in New York City than in, say, Rome or Milan by 1900 or 1910.”

Once it landed stateside, however, pizza remained a dish that was largely known within the community—not outside it. Pizza was often prepared as a snack at home, though full-fledged pizzerias opened up in various Italian-American hubs concentrated in the Northeast: northern New Jersey, New Haven, and of course, New York. But said pizzerias were primarily for southern Italians, by southern Italians. While Italian restaurants may not seem exotic now, in the 1920s and 1930s they weren’t attracting much of a WASP clientele.

That started to change after World War II, when Naples became a hub for British and American intelligence agents. During their time overseas, many troops developed a taste for Italian food, including pizza, and subsequently sought it out when they returned home—much to the confusion of restaurateurs, who didn’t understand what Americans wanted with a traditionally lower-class street food. Still, veterans played a role in popularizing pizza outside the Italian community.

Taking It National

With popularity inevitably comes industrialization, and pizza was no exception. The 1950s and 1960s saw the rise of fast food in America, and while the hamburger is typically considered the poster child of the standardization and rapid expansion embodied by restaurants like McDonald’s, pizza saw its own fledgling mega-chains in the form of Domino’s and Pizza Hut.

From the beginning, Helstosky explains, businessmen like Domino’s founder Tom Monaghan set their businesses up to be national franchises, emphasizing efficiency and uniformity across locations. Unlike traditionally independent, immigrant family-owned pizzerias, fast-food pizza chains were modeled around delivery and takeout rather than serving customers in their actual stores. Also, unlike older pizzerias, they were able to establish a presence in the Midwest, far away from American pizza’s traditional stronghold in the Northeast.

Despite their emphasis on pizza as “product,” however, fast-food chains did have one thing in common with their forebears: their customers. Domino’s began opening restaurants near military bases and college campuses, understanding that both soldiers and students were looking for the same quick, cheap meal as Neapolitan workers had been 200 years before them.

Pizza Goes (Mid)West

No history of pizza in America, however, would be complete without a sidebar dedicated to Chicago-style, which reached the Midwest—and shaped its preferences—long before Pizza Hut.

Even though deep-dish pies are referred to as “pizza,” they are actually descendants from another food entirely different than the thin-crust, Neapolitan pies of New York and Connecticut. Like the pizza margherita, Chicago pizza’s origins are hotly debated, but one theory holds that deep dish’s ancestor is actually the Sicilian dish sfincione, which Helstosky describes as “a deep-dish pie with tomatoes and cheese and other toppings layered into it.” The flaky, cheesy pies found at now-legendary places like Giordano’s certainly resemble the sfincione more than, say, a pizza bianca.

After Sicilian-Americans brought their pie overseas, it caught on both among other Italian-Americans and in the Midwest at large. This is why Pizza Hut and Domino’s, in an effort to appeal to Midwestern audiences, went national with “chewier, more substantial” pies boasting more toppings than the average Neapolitan pizza—thereby creating the hybrid pie most Americans grow up getting delivered to their front door.

Farm, to Woodfired Oven, to Table

While independently owned pizzerias—often operated by other immigrant groups such as Greek-Americans as well as Italian-Americans—never disappeared, fast-food pizza dominated the American landscape for several decades. The 1980s, however, saw the birth of the farm-to-table movement in California, an ethos that now dominates even fast food (Chipotle, anyone?), but arguably began with pizza.

Among its other offerings, Helstosky explains, Alice Waters’ Chez Panisse included “incredibly creative individual pizzas” assembled from farmed or foraged ingredients. In Los Angeles, Wolfgang Puck did more or less the same thing, sparking a trend that moved eastward over the past few decades—reversing pizza’s initial trajectory—and culminated in Brooklyn artisanal spots like Roberta’s.

In 2015, it’s easy to find locally-sourced, vegan, or even gluten-free pizzas that go for twenty dollars or more a pie. That’s a far cry from pizza’s humble origins as cheap fuel for laborers. But despite farm-to-table’s current popularity, the 2am dollar slice, we all know, remains eternal.