Lucian Perkins’ “Tent of Dreams” depicts Occupiers at McPherson Square hoisting a tarp over a statue of General James B. McPherson.

In 30 years of photographing protests in Washington, Lucian Perkins had never encountered a demonstration that lasted as long as the Occupy movement, whose participants camped in D.C. parks for several months through the winter cold.

He’d never found himself tracking his subjects through cryptic, 140-character missives, either.

“Twitter turned out to be really handy for me,” says Perkins, a former Washington Post photographer who, along with others, shot the encampments over the past year for the nonprofit photography collective Facing Change: Documenting America. “I subscribed to probably eight or nine Twitter accounts of people involved in Occupy, who wrote about what they were doing daily.”

The images he and other Facing Change photographers captured of Occupiers are now part of an exhibition at American University’s Katzen Arts Center. “Occupy This!” chronicles the first months of the loosely knit nationwide (and, eventually, worldwide) movement, that intended to call attention to perceived social and economic inequality and sprang up last fall following the Occupy Wall Street protests in New York City.

The collection puts together pieces of the beginnings of the movement (which, though still in flux, will mark its first anniversary Sept. 17). While the photos show what unfolded across the U.S., they can’t explain the particulars of a growing, often fractured political protest, says Alison Nordstrom, the exhibit’s curator.

“We can show you what Occupy looked like,” Nordstrom says. “Maybe we can even show you what it felt like. But pictures are not the best way to discuss the ideas behind Occupy, so we’re not really attempting to do that.”

The photos in the show — some of which, blown up to near-life-size proportions, cover entire walls — were chosen for their emotional impact.

“We picked them for a level of drama and the way the pictures created a feeling,” Nordstrom says. “As you move through the exhibition, our hope is that you end up feeling like you’re a part of it.”

In Andrew Lichtenstein’s photo “Occupy Wall Street,” a young man with a guitar sings a song (John Lennon’s “Imagine,” Lichtenstein says) as demonstrators flash peace signs. In Carlos Javier Ortiz’s “Occupy Chicago,” protesters make their positions clear with signs that read “We want democracy” and “The only thing that trickled down was your bulls**t.” Perkins’ photos from Washington include “Occupy D.C. Eviction,” a tense shot of armed police arresting Occupiers on Feb. 4, the day they were removed from McPherson Square (the protesters, however, maintained a presence in the area until June).

In the process of assembling “Occupy This!” Nordstrom became “sympathetic” to the Occupiers’ cause, she says. The show doesn’t takes sides but rather seeks to put the movement in a larger historical context — and give it a cohesion in retrospect that many critics accused it of lacking. From the start, the movement has avoided using a single voice. And the causes taken up — unemployment, rights for migrant workers, health-care reform, access to higher education — have been as diverse as the backgrounds of the Occupiers.

Nordstrom says it’s unwise to try to pin down the movement to any one goal. Still, “Occupy This!” has one simple mission.

“We’re really hoping for discussion,” she says.

Carlos Javier Ortiz captured “Occupy Chicago” last fall.

“Occupy Chicago”

Chicago-based photographer Carlos Javier Ortiz took this shot at a protest last fall outside the city’s Bank of America building and Federal Reserve. He says it was clear to him that the frustrations being vented would lead to longer-term action by a diverse group of people. “I saw a lot of blue-collar folks, grandmothers, senior citizens,” Ortiz says. “Cab drivers were beeping their horns. It was a collective where citizens started taking a stance.”

“Tent of Dreams”

Lucian Perkins captured “Tent of Dreams” on Jan. 30, when Occupiers at McPherson Square briefly hoisted a tarp over the park’s statue of General James B. McPherson in a challenge to park police, who had just restated their commitment to enforcing the prohibition on camping on federal park land. Perkins took a few snapshots from a distance and then found his way under the tarp. “I wanted to be there as they were still finishing erecting the tent,” Perkins says. “Symbolically, it was fascinating.”

Katzen Arts Center, 4400 Massachusetts Ave.; Sat.-Oct. 21, free; 202-885-2787. (Tenleytown-AU)