No other food can bring my family together like that. And no food is quite as compliant: my family's Christmas ham, which we simply drop into a roasting pan and coat with a brown sugar and mustard glaze, keeps giving right on through to New Year's, in sandwiches, pastas, fried rice, mac-and-cheese, beans, greens, soup, and whatever else we feel inspired to make with it.

Simple a pleasure though ham is, it's also complicated in its way. The ones that I grew up eating in New York on holidays—sweet and juicy and pink, with a crackly, caramelized crust—are worlds apart from the country-style hams that my husband, Lindsay, was raised with in North Carolina. His family's hams are complex, salty, and wonderful in a completely different way. Ten years ago, when I was first handed one of the hams Lindsay's uncle Kent cures in salt in the fall and leaves hanging in his barn until the following year, I have to admit, I was scared by the sight of it. It was hard to the touch, and part of it was specked with mold. I followed Kent's instructions to scrub it clean; then I removed the two bottom crisper drawers of my refrigerator and stored the thing there until I mustered the courage to cook it. Cleaned up, it looked more like the serrano hams I've seen perched on tapas bars across Spain or the prosciutti that hang in salumerie all over Italy, both of which are shaved thin and eaten uncooked. Suddenly I wondered, Why couldn't I eat Uncle Kent's ham the same way?

Cookbooks were of little help. James Beard, who was probably the most devoted ham champion this country has ever seen, acknowledges in his book American Cookery (Little, Brown, 1972) that the coveted salt-cured hams of Europe—Belgium's Ardennes ham, France's Bayonne ham, Germany's Westphalian ham, Parma's prosciutto—are traditionally served uncooked. But when it comes to American dry-aged country ham, like the ones Lindsay's relatives have made for centuries in the South, Beard told us to cook it. That's the way it's always been done. Uncle Kent agreed. "I guess you could eat it raw," he told me over the phone. "But I never do." Instead, he told me to saw off the hock and save it for seasoning soups and beans, slice off a few pieces for pan-fried ham steaks, and then soak the ham for a few days before simmering, glazing, and baking it. And so I did. (I had to borrow a handsaw from my apartment building's superintendent, Charlie.) The results were delicious, but I couldn't resist shaving off a few pieces first to eat raw; they had a gentle salinity, and they practically melted on the tongue. Dry-curing the hind legs of pigs is one of the oldest ways of preserving pork, and—with all due respect to Uncle Kent and James Beard—it does indeed render the meat ready to eat. The ancient Romans did it. The Gauls did it. And some historians believe that those Europeans learned how to do it by trading with the Chinese, who have been curing hams for millennia. Salt-cured hams are a traditional holiday food in scores of countries, from France and Germany to England and the United States, and a love of ham in those countries has traveled to the Caribbean, the Philippines, South America, and beyond. The meat and bone from hams are put to use in myriad ways—in Chinese ham broth soups and in German baked ham steaks, to name but two. Ham pairs beautifully with sweet, spicy, or creamy foods; those foods counteract the meat's saltiness, which can range from mild to emphatic (see Ham Companions).

The process of curing ham—whether covering it with salt and letting it age or wet-curing it with a brine solution—is pretty straightforward (see A Simple Science), but a lot of other factors lend regional and stylistic differences: the breed of hog and what it eats; the kind of salt or pepper and how it's applied; whether sugar is mixed into the cure; whether the meat is smoked in addition to being cured; and so on. "Ham is one of our most fascinating and varied native foods, Beard writes in Beard on Food (Knopf, 1974). "One never tires of eating it."

He wasn't exaggerating. In the decade since I tackled Uncle Kent's ham, I've cooked long-cured hams bought from Southern truck stops, eaten quick-cured smoked hams from Russian butchers, and met with other ham lovers to savor contraband jamon iberico from Spain (now imported legally, thank heavens). I've sent countless honey-baked spiral hams to friends who are mourning, birthing, or undergoing an IRS audit. I've compared the flavors and textures of uncooked country hams from Kentucky, North Carolina, Tennessee, and Virginia, and I've walked through aging rooms where the wood beams are slicked with centuries' worth of ham fat.

Until recently, though, I had never been to Smithfield, Virginia, or Parma, Italy—arguably two of the most important capitals of cured pork in the world—to eat ham. So, this past fall, I made pilgrimages to those places, each within a week of the other, to understand the glories and nuances of the world's greatest hams.

Almost everyone I met in Smithfield, a town of 7,000 people on the James River with a picture-perfect main street, had something to do with ham. On a Friday night, the bar at Smithfield Station, one of two restaurants downtown, was crowded with employees from Smithfield Foods, the largest pork processor in the world, drinking beer and eating ham biscuits. At a nearby table, Henrietta Gwaltney, the great-granddaughter of the legendary Smithfield ham producer P. D. Gwaltney (see Man's Best Friend), was dining with her two grown children.

Smithfield is where American ham began and where its evolution has played out for the past four centuries. Jamestown, site of the earliest English colony in North America, is just a few miles upriver; the settlers who brought pigs to the New World started confining hogs on a nearby island, called Hog Island, to raise them for ham, and in 1779 a sea captain named Mallory Todd started to ship hams from Smithfield to the British West Indies. The Virginia trade eventually spread to England, where Queen Victoria placed a standing order for six a week.

Smithfield had all the right conditions for ham making. It had the hogs: a flavorful, fatty razorback variety. It had cheap feed: peanuts, which grew in abundance and gave the hogs a uniquely nutty flavor. It had access to the sea (for salt) and to the James River, which allowed for easy transport. And it had the perfect climate: hot during the day and cool at night, with the four seasons necessary for hams to undergo a proper curing.

Smithfield also had some savvy marketers, who starting promoting local hams in the early 1900s. In the 1930s, many of the tourists flocking to visit the newly restored colonial Williamsburg settlement nearby were going home with Smithfield hams. Immigrants looking for hams like the ones from their homelands started buying them, too; Chinese-Americans, for instance, found them to be a fine-tasting substitute for their smoky Yunnan and Jinhua hams. Smithfield hams and, by extension, Virginia hams became foods with a coveted pedigree.
In the 1930s and '40s, ham production, and ham itself, started to change. With the advent of refrigeration, temperature-controlled aging rooms could replicate the changing of the seasons, so country hams could be produced year-round. More important, refrigeration allowed for the production of lightly cured "city" hams, which were injected with brine to speed up the curing process and shipped in refrigerated railcars. Many Americans fell in love with the sweet flavor of city hams, and producers churned them out in great numbers. Smithfield, by then the pork capital of the country, boomed. Over time, a single company—now called Smithfield Foods—became the principal producer in town. Even though the company now processes some 20 million hams a year, only 45,000 are the dry-cured, hickory-smoked Genuine Smithfield hams, which hang for at least six months in a facility I toured with Larry Santure, the company's senior business manager for dry-cured meats. "It's all still done by hand," he said, as we passed the three-story-high, smoke-charred closets where hams were dangling. "The only thing that's changed is that years ago there was a mule team that pulled pallets of ham to the second floor."

Even though city hams are far more common, the long-cured country kind is what everyone in Smithfield seems to prefer. "You wouldn't think to entertain without it," Janice Scott, a 74-year-old home cook and caterer, told me over ham biscuits at the Smithfield Inn, a bed-and-breakfast and restaurant. When she doesn't simmer and bake one of Smithfield's hams, she says, she goes for a milder, dry-aged Edwards ham, cured 20 miles away, in Surry.

I've long been a fan of Edwards hams; they're smoky and a bit sweet, with a salinity that tickles but doesn't torch the tongue. When I visited the Edwards smokehouse and country store, the third-generation producer, a genial 53-year-old named Sam Edwards, served me his new release: a 16-to-24-month-aged ham, made from fatty Berkshire pigs; he suggests eating it raw. Called Surryano (a pun on serrano and Surry), it's silky and intense, the perfect thing to wrap around a piece of melon—but that's not how most people eat his long-aged hams.

Edwards took me across the James River on the nearby Surry-Jamestown ferry (which his great-grandfather used to own and operate), then over to the Old Chickahominy House, a restaurant in Williamsburg. Its owner, Maxine Williams, who's worked there for 40 years, sells about 600 biscuits a day made with slices of cooked Edwards ham. Each of her rectangular buttermilk biscuits is a thing of beauty, enveloping slices of luscious ham and browned under the broiler before hitting the table. Williams let me into the kitchen just as one of her cooks, Tony Canaday, was beginning to maneuver his knife around the bones of a 14-pound Edwards ham, which had been simmering for four hours. I asked whether she'd ever bought boneless ham. She shook her head. "Cooking it on the bone keeps it juicy." Then I asked what she did with the scraps. "Ground ham!" she said, as if I should have known. "I sell a lot during the holidays for hors d'oeuvres."

Like folks from Smithfield, the people of Parma, a bustling city of 180,000 in Italy's northern region of Emilia-Romagna, know ham: when I visited last fall, I was struck by how everyone I met knew what producer they like the best, what length of curing suits their tastes, and how to make an outstanding ham sandwich—the local torta fritta is a pillow of lightly fried dough stuffed with shaved prosciutto, whose creamy fat melts into the warm bread. Just south of Parma, particularly in the town of Langhirano, ham is big business. Some 200 producers cure about 9 million hams a year. Most of the hams they make aren't cured in salt for as long as American country hams are, and they aren't smoked, so their flavor is softer, sweeter, and decidedly less salty. Still, I visited a few of those producers and was struck by just how similarly ham-making techniques had developed over the centuries here, halfway around the world from Smithfield. Sure, there are techniques that are distinctive to Parma: there's the sugnatura, or covering of the exposed flesh in lard, and the fact that producers open windows in the aging rooms to let the dry breezes wash over their hams. And there are numerous differences in temperature, humidity, and type of salt used. But the equipment and the aging rooms in Smithfield and Parma seemed remarkably alike.

Italians also produce prosciutto cotto—a cooked quick-cured ham—that tastes a lot like our boiled or baked city hams; it is stuffed into arancini (rice balls), tossed with pasta dishes, and draped over pizza. In fact, almost all dry-aged ham in Italy used to be cooked, just like ham in the American South, as I learned at a museum in Langhirano dedicated to prosciutto. There, I stumbled across a display of recipes from the Middle Ages that called for cooking ham in water or wine; the museum guide pointed out that cooking was merely a precautionary measure against the contamination that sometimes occurred when hams weren't cured properly. In the 1870s, when producers switched from local pigs to a faster-growing English breed, ham makers found that the meat cured more consistently and could safely be eaten raw. After that, uncooked prosciutto di Parma quickly became a luxury food.

As I traveled around Parma and its environs, stopping in at salumerie where butchers sold their own, house-made prosciutti, I couldn't help thinking about the smaller producers I'd encountered around the American South, the ones who cure just a few hams a year and hold fast to the old ways. I met a lot of people like that in Italy, but none made more of an impression on me than Massimo Spigaroli, a chef who is known for his culatello ham, a smaller, boneless cousin of prosciutto made north of Parma with the prized central portion of the haunch. His restaurant, Al Cavallino Bianco, is situated on a working farm along the river Po where his great-grandfather used to raise hogs and cure hams, just as Spigaroli does today. Down in the cellar where his hams hang, he pointed to a high window where a cool, humid wind was rushing in from the river. "Culatello needs this humidity," he explained.

Later, sitting in the restaurant's rustic dining room, I was overwhelmed by the richness and deep flavor of Spigaroli's culatello. Like the best hams—whether from Virginia, an Italian hill town, or Uncle Kent's backyard—they distill the essence of the place where they're made.