The current Off Broadway revival of “Angels in America,” the seven-hour epic subtitled “A Gay Fantasia on National Themes,” isn’t the only play on the boards in Gotham with national themes on its mind.These days Off Broadway is rife with shows that take on the nation, with Lisa Kron’s “In the Wake,” Richard Nelson’s “That Hopey Changey Thing” and Amy Herzog’s “After the Revolution” among the productions that look at the ways the personal and the political intersect. All three of those plays are set within the past decade or so, and it’s no coincidence that all share a dark-night-of-the-soul melancholy regarding the legacy of the left. That topic’s been prominent during a midterm election season in which voter disappointment with President Obama proved a major topic of conversation. “For people who want to write big plays about the world, it’s scary right now, and it’s really motivating,” says Leigh Silverman, helmer of “Wake,” now playing at the Public. “Wake” centers on a politically engaged young woman, with the news events of the day — beginning with the contentious 2000 presidential election — serving as a prism through which the events in her personal life are viewed. Herzog’s “Revolution,” now in a Gotham run at Playwrights Horizons, chronicles a family in the wake of published revelations about the morally questionable activities of a late, well-known relative. The story is based loosely on the scribe’s extended family history. The writer set the play in 1999, just prior to the Bush years that proved so deflating to the left. “In 1999, we were feeling totally disillusioned and disenfranchised before we really were,” Herzog says. “It seems like an amazing irony, thinking about what would happen a couple of years down the line.” As soon as politics and other topical concerns hit the stage, creatives often wonder whether raising such issues will limit a play’s shelf life. That’s especially true for “Hopey Changey,” a family drama set on the night of Election Day, Nov. 2, 2010, that began performances at the Public a week prior. “It’s a lot of investment to put into something that could be disposable, and it’s not the smartest commercial strategy,” Nelson says of his decision regarding when to set the play. Still, he gave priority to the conceit’s immediacy, hoping to counter the noise of most political discussion these days. “In general, the country is having a very loud discussion without most people listening to each other, and I wanted to get a real, human, confused voice in on the conversation,” he says. Nelson, who began writing the show in late June, says few of the show’s political concerns changed as the play, and current events, developed. Eventually he added in gubernatorial candidate Carl Paladino’s name, and he also penned some unused lines about the weather in case it happened to rain on Nov. 2. (It didn’t.) Meanwhile, the flux of current events had a few advantages over the years for “Wake,” whose central character has definite opinions about the U.S. financial regulatory system. In earlier versions of the show — prior to the economic meltdown — many details about the regulatory system had to be explained thorough chunks of exposition. Now? Not so much. All that explanatory dialogue got cut. “We all know what the regulatory system is now,” Silverman says.