From listening to the Republican and Democratic national conventions, one might surmise the economy is an issue in this election.

Well, if that’s the case, the makers of “Detropia,” a documentary being released Friday in Washington at the West End Cinema, have an elegiac case study to ponder.

The movie, which focuses on the travails of Detroit, comes complete with the kind of regular folks both political parties say they are fighting hard for: a retired teacher who runs a blues bar, a local union president, a waitress who has a video blog, scrap-metal hunters and even outgunned urban planners.

And they have plenty to say about the auto industry bailout, the manufacturing base in the United States, government’s role in providing social services, the entrepreneurial spirit and the decline of the middle class.

“The people we focused on were black middle class, who decided to stay for one reason or another … primarily because they love the city, a city that was the birthplace of the black middle class,” the film’s co-director, Rachel Grady, tells HOH.

Detroit’s woes are familiar to those with even a passing interest in the American 20th century. In 1930, it was the fastest-growing city in the world. By 1950, with American prosperity growing, and with it an appetite for cars, the population topped out around 1.8 million. In the intervening years, the auto industry collapsed, urban blight took over, and the Motor City’s population after the 2010 census had contracted to 713,000.

The filmmakers, Grady and Heidi Ewing, make the case that Detroit might be where the rest of the United States is heading.

“I think we’re seeing critical mass happening, and Detroit is the epicenter. … It’s about 20 years ahead of the curve, and hopefully people can learn from that, especially the disintegration of the middle class in this country,” Grady says.

Automakers last week announced strong sales numbers for August, providing Democrats who supported the auto industry bailout fodder against their GOP rivals who opposed it. Grady, though, said she still wonders about the overall economic model. “What is more relevant is, how many jobs has that translated into? … How is that going to help the man in the street?” she says.

With the rebound of the auto industry and some other signs of life in the city, the news isn’t uniformly bad. But the movie doesn’t present a case that things are definitely getting better or worse, allowing its subjects to ponder what an uncertain future might hold for them.

One shot in the movie lingers on an old auto parts shop, the signage of which has faded and some of which has been filled in with spray paint to read “UTO PIA.” Asked whether finding this shot helped with the film’s title, Grady says it did.

“Naming this film was extremely challenging. We were definitely inspired by that. It’s either derived from ‘dystopia’ or ‘utopia.’ It’s your choice. … We leave it up to the viewer to decide,” Grady says.