(Martín Elfman for The Washington Post)

Is Washington a major theater town, or is it a collection of isolated theater clubs? A long-term study of the area’s top theaters generated a startling figure: A whopping 85 percent of audiences patronize a single troupe.

“We weren’t surprised,” says Edgar Dobie, executive director of Arena Stage.

The idea that Washington theater audiences may cluster in silos also didn’t seem to faze Jill Robinson, president and chief executive of the Colorado-based consulting firm TRG Arts. “It’s consistent with virtually every study we do,” Robinson says.

TRG Arts looked at 10 seasons of ticket-buying data pooled from 2004 to 2013 among seven major D.C. theaters: Arena Stage, Ford’s, the Shakespeare Theatre Company, Signature Theatre, Studio Theatre, Theater J and Woolly Mammoth. In part, the companies wanted to know whether they were carving one another to bits as many of them substantially expanded operations during the period, enlarging facilities and challenging audiences to buy more seats.

The results pointed to a 13 percent increase in theatergoing households and a 25 percent increase in households buying single tickets. It even showed that D.C. theater outpaces the national rate of getting audiences to buy subscriptions — the companies realized a 20 percent increase during the decade in question.

“Too much theater: Is there such a thing?” asks a slide at the top of the report that Robinson presented. The reassuring answer seemed to be “not yet.” Even increased ticket prices, TRG found, have not overtaxed the market.

For Robinson, the issue is keeping audiences the first time they visit. She describes a “magic math” that happens when patrons can be lured to more than one performance, and to more than one theater, per year. Repeat attendance jumps and attrition dives, yet the art of keeping audiences is often lost, as organizations fret about attracting fresh faces.

“It’s a gong that we clang,” Robinson says, warning against too much “prospecting” for brand-new clientele. “If we date, and you don’t ask me out again in a few weeks, I’ll forget how cute you are.”

That means encouraging audiences to go to any theater, following the “rising tide lifts all boats” philosophy. It can be a bit counterintuitive for chronically embattled nonprofit arts organizations long in the habit of primarily looking out for themselves.

From left, Esperanza America, Elia Saldaña and Fidel Gomez in Karen Zacarias’s “Destiny of Desire” at Arena Stage during last year’s citywide Women’s Voices Theater Festival. (C. Stanley Photography)

“It’s the fear that if I introduce you to my friends, you’ll like them better than you like me,” Woolly Mammoth managing director Meghan Pressman says.

Robinson’s message is that mingling expands the party. And there are reasons to think the limited terrain of TRG’s seven-troupe study, concluded three years ago, understates how often ticket buyers already play the field.

“It’s very rare for me to find a theater that doesn’t have significant crossover,” says Mark Shugoll, chief executive of Bethesda’s Shugoll Research.

“I suppose maybe we only subscribed to one theater at a time,” says Carol Muskin, 58, a longtime D.C. theatergoer who recently moved to Chicago with her husband, Chuck Pierret. Over roughly two decades, the couple variably subscribed to Arena, Signature and Shakespeare Theatre Company. But, Muskin adds, “We’d definitely go to shows at other theaters.”

The large tourist audiences at Ford’s Theatre, a historic site and a national destination, probably boost the number of one-time purchasers in the area, inflating the image of theaters hoarding a single audience. The same might be true of the large, nationally known Shakespeare Theatre and Arena Stage, both with more than 1,200 seats in their multistage operations.

Round House Theatre has discovered that STC and Arena are the two troupes it most shares audiences with, despite contemporary programming at Round House that’s more in line with work at Woolly and Studio. Woolly found the same thing: More of its audiences are shared with STC (21 percent) and Arena (30 percent) than with any other troupe.

“Shakespeare and Arena are the two largest theaters in town,” says Ed Zakreski, who became Round House’s managing director in July after serving as STC’s chief development officer. “So maybe it’s just an odds game.”

“The larger enterprises tend to feed the whole ecology,” Dobie says, adding that Kennedy Center theater was not part of the TRG survey.

“Man of La Mancha” last year at the Shakespeare Theatre Company, which has lately added musicals to its menu. (Scott Suchman)

Signature Theatre points to a natural overlap with Kennedy Center audiences because both present musicals. Shugoll found substantial crossover in the recent online surveys he conducted for Signature and Round House: In the two-year Round House survey, 43 percent of single-ticket buyers had been to four or more theaters within a year, 59 percent went to three or more, 76 percent to two or more, and 91 percent went to at least one theater other than Round House. That does not include attending the big touring houses (the Kennedy Center, the National Theatre, the Warner Theatre), which further raises the figures.

“Audiences are highly educated and very smart,” says Shugoll, who reasons that musical theater fans attending the upcoming “The Secret Garden” at STC may also be interested in “Carousel” at Arena, “Titanic” at Signature and “Caroline, or Change” at Round House. “They know what they like. They’ll find it.”

None of that invalidates TRG’s hard “transactional” data, drawn from purchases and organizational records. And everyone seems invested in Robinson’s takeaway about working to strengthen not just individual institutions, but the group.

“It reaffirmed importance having a strong Theatre Washington in our midst that can make sure our impact is understood,” Dobie says of the organization that promotes D.C. theater and oversees the annual Helen Hayes Awards.

“We all believe that, which is why you see us collaborating more all the time,” Signature managing director Maggie Boland says.

Examples seem to be growing. Signature and Round House cross-promoted the musicals “Jelly’s Last Jam” (recently at Signature) and “Caroline, or Change” (with Signature talent working at the Bethesda stage). Round House just partnered with Olney Theatre Center on a co-production of the two-part, seven-hour “Angels in America,” presented at Round House and geared to moving patrons between the two troupes. Next year, the organizations will team up again — sharing infrastructure, artists and audiences — for a show at Olney.

Mitchell Hebert and Craig Wallace in the world premiere of Jessica Dickey’s “The Guard,” at Ford’s Theatre last year. (Scott Suchman)

Shakespeare Theatre Company’s executive director, Chris Jennings, who initiated the TRG study, notes that niche theaters have been broadening their programming in an effort to reach wider audiences. Lately, STC has been producing musicals and has expanded its international offerings, and Jennings points to Yael Farber’s daring reinterpretation of “Salome” during last season’s citywide Women’s Voices Theater Festival as an instance of “reinvigorating the classics” while diversifying the company’s audiences, especially among Generation X and young-professional demographics.

Ford’s Theatre also broke its mold during last year’s citywide festival of premieres by women. Jessica Dickey’s “The Guard” was among the festival’s most intriguing dramas, and among the most unexpected at the theater.

The citywide festival mentality kicked in again as Arena, the Kennedy Center, Studio Theatre, STC and Signature coordinated “Theatrical Selections,” a series of free Monday-night readings of political scripts running in tandem this fall with the ongoing spectacle of the general election.

The next Women’s Voices festival has not been announced, but plans seem to be well underway for a winter event next season. Amy Austin, executive director of Theatre Washington, is among several people who mention the dream of creating a subscription package that lets audiences roam among several companies, and not just during a festival. The logistics are daunting: Last year’s Women’s Voices fest, with a whopping 50 outfits on board, proved that.

Even beyond the core seven troupes that TRG studied, Washington theaters make it their business to be different — in style, in size and in price. Finding the portals to smoothly propel audiences from one stage to another is the ongoing challenge.

“If it was easy,” Jennings says, “we’d already be doing this.”