The 2006-2007 District of Columbia Yellow Book has, like all Yellow Books, a map of the coverage area right on the cover. Because listing all 120-plus District neighborhoods on the tiny yellow diamond would make for a cluttered mess, the map ticks off just 13 of the best-known areas in D.C. Among them: Georgetown, Cleveland Park, Tenleytown, Congress Heights, and…“Terra Cotta.”

On the Yellow Book map, the name is placed in Northeast, just shy of the Prince George’s County line, but Terra Cotta is not listed on any city-published neighborhood directory and is not named on most standard maps, including those of the most popular brand, ADC. And a random sampling of people hanging out at the Fort Totten Metro on a recent weekend discovered that no one knew what on earth Terra Cotta was, let alone that they were standing right on top of it.

The neighborhood has been listed on the cover of the D.C. Yellow Book for as long as the company has published a directory for the city—since 2004—and Yellow Book says there’s no mystery as far as it’s concerned. “Terra Cotta appears on maps from the U.S. Board on Geographic Names Web site as well as Rand McNally,” writes Yellow Book spokesperson John Hartz in an e-mail. “The map on the directory cover is based on and in keeping with these commonly accepted resources.”

According to an undated U.S. Geological Survey map, Terra Cotta is listed as an area between North Capitol Street and Eastern Avenue, which encompasses Fort Totten Park, Backus Junior High, the Fort Totten Metro, and other landmarks that, according to current designations, fall under the neighborhoods of Lamond-Riggs and Queens Chapel. It was added to the federal government’s official database of place names in 1979.

The name Terra Cotta comes from an ­earthen-tile factory belonging to Angus Lamond, a land owner who once possessed a good deal of acreage in the area. The tile factory sat somewhere near where Underwood Street and Chillum Road now intersect, according to Historic Takoma, a neighborhood preservation group. When the Baltimore & Ohio Railroad used to stop in the neighborhood, the Lamond station was nicknamed the “Terra Cotta” station because of the factory.

That was, of course, a long time ago—turn of the 20th century. Even if the area was known as Terra Cotta long after the B&O gave way to Metro and the factory disappeared, and even if Yellow Book graphic designers are finding Terra Cotta listed on a couple of maps, why choose some obscure neighborhood name that is no longer used? Why not highlight some other Northeast D.C. neighborhood? Why not Michigan Park? Chillum? Woodridge?

Hartz has no good answer to that question: “The map on the cover of the directory is based on a cross section of the information provided through [those] widely accepted resources,” he explains. “As such, it is meant to serve as a representative sampling.”

But it’s difficult for a neighborhood to be reflective of the city as a whole when no one knows what or where the hell it is—even those who live right inside of what the Yellow Book folks might call Terra Cotta proper.

At a recent Sunday afternoon meeting of the Northeast D.C. Historical Society, several residents from the neighborhood gathered to talk neighborhood heritage. If anyone would know something about Terra Cotta, it would be this group. Most of them bought their homes in the late ’50s. They remember when Abe Pollin left the neighborhood for the ’burbs. They remember when the Lamond-Riggs Library they’re sitting in was built. But they don’t remember anyone ever referring to their neighborhood as Terra Cotta.

The only person at the meeting who knew anything about Terra Cotta was Diana Kohn, a reporter and history buff who was also trying to find out some additional information about the little-known neighborhood name and show what she had learned in her search.

“The librarians didn’t know, either,” says Kohn. “And I was told that the file [on Terra Cotta] was lost.”

Although Hartz says Yellow Book has never received any inquiries about the long-lost ’hood, its appearance has brought about a quest to figure out when and if the name Terra Cotta was ever widely applied to a particular piece of Northeast.

In a recent thread of H-DC, an Internet discussion group for D.C. historians, several D.C. residents and history experts chimed in on the Terra Cotta puzzle.

Group members confirmed the existence of the terra cotta factory in the area between Fort Totten Park and P.G. County and also mentioned the factory closed down in 1955.

Historic Takoma president Sabrina Baron noted that many pipes and fixtures in homes surrounding the plant were made at the terra cotta works. Yet, she said, from what she understands about the location of the terra cotta plant, any neighborhood called Terra Cotta shouldn’t be in Northeast.

“Terra Cotta should be in Northwest,” Baron wrote.