Editor's note: American barbecue culture is mindbogglingly diverse. What differentiates your Carolina whole hog from your Texas brisket? Southern food sage Robert Moss is here to lay it all out, element by element. First up: the smoker.

The rich variety of American barbecue can be attributed to many factors—the kind of wood used, the types of meat selected, and the way that meat is seasoned, cooked, and served. But the differences between one regional style and another begins long before the brisket or pork shoulder ever encounters smoke and heat, and that's with the design and construction of the barbecue pit itself.

Pits tend to evolve in complexity as you move from east to west. Eastern North Carolina and the Pee Dee region of South Carolina is the home of whole hog barbecue, and the pits its leading practitioners use are not far removed from barbecue's original native American form: a trench dug directly in the ground (which is the origin of the term "pit" in the first place.)

By the time you reach Texas, the pits can more accurately be called smokers, which use indirect heat from an offset firebox to slow-smoke the meat. Many restaurants use commercially-manufactured models from companies like Bewley and Oyler, which offer automatic air control systems and motorized rotisseries, while other pitmasters have their own customized pits whose construction details they consider highly-sensitive trade secrets.

Here's the scoop from some of the most noted barbecue cooks in the country about the starting point of their craft: the pits. This time around, we're focused only on those who use wood-fired pits. We'll take a look at the newer gas- and electric-assisted pits in a later piece.

When it comes to the pits at the Skylight Inn in Ayden, North Carolina, Samuel Jones emphasizes their simplicity. "They're just standard masonry pits," he says. "We've been cooking the same way since we opened."

Each long rectangular pit has thick brick walls and is open at the top, with iron rods to hold the split whole hogs. There's not even an opening at the bottom for adding coals: they're simply scattered by the shovelful around the pigs so they fall to the floor of the pit. "There's metal lids that hinge on the pit itself," Jones adds, "Which we lower while the meat's cooking."

As the fame of Skylight Inn grew and volume increased, they had to add more capacity, and now they have two pit houses in operation. "One house was built in the '70s," Jones says, "and one house was built in the late '80s or early '90s. We finally tore down the original pit house four years ago because they had dirt floors and we hadn't used them in forever."

The pits at Scott's Bar-B-Que in Hemingway, South Carolina, are similar in design, though they've evolved a little over the years. "We started with a little brick pit," says Rodney Scott, who now runs the business his father started back in 1972. "And then my dad added a few more. The original pits I remember were little brick stacks with rebar to hold them up. He had the cinder block pits built a little bit later on." Each pit can hold two whole butterflied hogs, and they're covered by a big sheet of metal that is lifted away and leaned against the cookhouse wall when Scott needs to flip or baste the meat.

At both Scott's and Skylight Inn, they burn wood outside the pits to create the coals that provide the heat. "We burn [logs] down in chimneys," Samuel Jones explains, "Then as it it produces the coals they are fired into the pit." Those chimneys are essentially brick fireplaces similar to what you might find in a house, and they carry the smoke and heat from the burning logs out of the pithouse.

The system is even more basic at Scott's, where they use contraptions they call "burn barrels"—huge repurposed industrial pipes set upright on the ground with steel truck axles inserted through holes near the bottom to create a sort of grate to hold burning logs. The barrels are situated out behind the cook house, and the men tending the pit scoop glowing red coals from the bottom with long-handled shovels and carry them into the cook house to scatter beneath the pigs through an opening at the bottom of each pit.

These details of pit design helped determine the characteristics of the finished food. The broad, open pits like those used by Samuel Jones and Rodney Scott are naturally suited for accommodating 150 pounds worth of whole hog. When hot embers are scattered beneath the meat, they cook with a direct heat, giving the meat a crusty, thick outer layer (what North Carolinians call "outside brown") that's imbued with smoke while the inner meat stays moist and mildly flavored.

Rodney Scott points to an addition effect of direct heat, too. "I have this theory," he says, "That when the juices of the hog fall into the wood it creates a whole new thing. They steam up the flavor of smoke back into the meat."

As one moves westward into the Piedmont of North Carolina and southward into Georgia and Alabama, the pits tend to be more elaborately constructed, and the wood that fires them is often burned right inside the pit.

"In the restaurant we have elevated brick coffin pits with large metal lids that are counterweighted and raise up and down," says Chris Lilly of Big Bob Gibson in Decatur, Alabama. "It's three layers of brick with insulation between the three layers . . . and heavy gauge metal along the sides."

The pits are heated by logs that are burned in a firebox on one side of the pit. "We have two chimneys," Lilly explains "One's beside the firebox, and on the other side we have another smaller chimney where we can bleed the heat and the smoke as we're cooking." That second chimney draws the heat and smoke through the pit and over the meat as it cooks. And the size? "They're absolutely huge," Lilly says. "We can cook up to 75 chickens at a time on each of our brick pits."

As you move down into Texas, slow smoking and carefully-regulated heat is the name of the game, and many barbecue restaurants employ big metal cookers with a range of designs—huge barrel-like cylinders with hinged lids, locker-like metal cabinets with stacks of racks inside. Smoke and heat are funneled by pipe or chimney from the fire box, a process called indirect smoking.

Some cooks, like John Lewis at Austin's La Barbecue, can get downright secretive about how their pits are constructed. When Lewis took over the pitmaster duties at La Barbecue, he wasn't satisfied with the metal pit he inherited. "It wasn't cooking brisket the way I wanted it to," he says. "So I just built a new one that would do it the right way. The new one is aerodynamic on the inside, everything about it is made to make the heat work."

"The cook chamber is made out of a decommissioned 1,000 gallon propane tank, with a firebox on the right and a chimney on the left. Much more about that I can't really tell you."

What Lewis will reveal, though, is that the key is what's inside that big tank, a proprietary design that creates an incredible draft from the firebox, pulling heat and smoke across the cooking meat and out the chimney. "There's nothing mechanical or anything," Lewis says. "It has such an incredible draft that the smoke doesn't sit in there very long."

Modern offset/indirect smokers lose that effect of juices dripping directly onto coals. They do, however, offer more precise temperature control, which is needed for turning a persnickety cut like brisket into tender barbecue. When logs are burned in attached fireboxes, more smoke gets sent across the meat than in pits fired with glowing embers, so the meat tends to have a thicker red smoke ring and a more intense smoky flavor, too.

The pits, of course, are just the beginning. In future installments we'll take a look at each of the other elements that make America's regional styles of barbecue so deliciously unique.

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