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The life of a downtown sidewalk can take some unexpected turns. One day, it’s mostly empty, save for a few sweaty suits making their way to Au Bon Pain or Five Guys. The next, it’s bearing the weight of three dozen office workers queuing up for the right to exchange $10 for a vaguely South Asian pita wrap.

If the District’s food trucks seem to show up at new locations as spontaneously as the flocks of seagulls that appear on various D.C. blocks on winter mornings, it’s because there’s more than a casual resemblance between the two species. Restaurants on wheels, it turns out, exhibit their own kind of herd mentality. Where one might expect mobile food vendors to sneak slyly onto new corners where their covert market research has shown customer potential, they often do just the opposite, reaching out before a new venture to the very people you’d think they’d be trying to outsmart: the other food truck operators.

Photograph by Darrow Montgomery

“We’ll either tweet or email each other and say, ‘Hey, you want to get together for a hookup or mini food truck party at 18th and Pennsylvania?,’ or something like that,” says D.C. Food Truck Association chairman and Red Hook Lobster Pound co-owner Doug Povich. “The reason is that it’s demonstrably better business when you have two or three or even four trucks.”

The power of the herd works in two ways. The first is visibility: If would-be patrons see a bunch of trucks on a certain corner one day, they’ll be more confident of finding trucks there the next. Second, diversity allows the food truck operators to capitalize on the fact that customers move in their own kinds of herds—say, the National Association of Dental Filling Manufacturers herd. If a group is going out to lunch and one is allergic to lobster, Povich says, they’ll all pass by his truck in favor of a sandwich shop if his is the only truck around. If there are multiple trucks, the group will split up among them, Povich will get a few customers, and the brick-and-mortar restaurants will have to content themselves with a complaint to the Department of Consumer and Regulatory Affairs.

“There’s a benefit in numbers,” says Curbside Cupcakes’ Kristi Whitfield, “because maybe somebody came out for a slice of pizza and decided they wanted dessert.”

But if a spot becomes oversaturated with trucks, some of the vendors—usually the junior members of the herd—are forced to seek out less-crowded pastures to avoid succumbing to the competition.

“In general, somewhere between three and eight trucks is an ideal number of trucks to be in the same space,” says Justin Vitarello of Fojol Brothers.

One space that’s often above capacity is the intersection of 12th and G streets NW. “A while ago, things were getting crowded at Metro Center,” recalls Whitfield. “So a few of us got together and said, ‘Hey, let’s get together and go a block away.’” Curbside Cupcakes, DC Empanadas, TaKorean, and a couple of others moved to 13th and F, where it took some time to gain traction. “It was probably a little too ad hoc,” Whitfield says. “We didn’t advertise in advance.” But nearby customers were ultimately grateful to be spared the onerous two-block walk to 12th and G.

Povich encourages food trucks operators to expand into new territory—it’s an important way for the young industry to keep growing. Recently, he says, food trucks have begun serving buildings like the Department of Employment Services on Minnesota Avenue NE, the Department of Housing and Community Development in Anacostia, the Martin Luther King Jr. Memorial Library, and the Wilson Building.

Still, not any old truck can venture into a new area and expect success; the formula for survival is more Darwinian. “Only the stronger trucks can afford to go to those places and develop them,” Povich says. “But we think, as an association, it’s important to do that.”