Detroit, Kathryn Bigelow's new film set during the Detroit Riots of 1967, isn't really about the famous city. Instead, the movie focuses on the Algiers Motel, which might help explain where Detroit was filmed: Boston. Instead of going to Detroit, Michigan, to recreate the events of the terrifying uprising, Bigelow took her production to a very different city for an interesting reason.
Despite the fact that the film is deeply rooted in Detroit history, Detroit was filmed in Boston, over 700 miles away from the city where the film is set. Though originally set to make the movie in Detroit, tax laws forced the filmmakers' to movie their production across state lines. "We originally located it in Detroit, but the tax-credit program had just been disbanded so we went to Massachusetts, to Boston, and shot the movie there," Bigelow said in an interview with The Boston Globe. (The state of Massachusetts provides tax credits to filmmakers while Michigan does not provide incentives for productions to come to the state.) Though Bigelow and the production team did reach out to the city of Detroit about filming bits and pieces (likely exterior shots), according to a report from the Detroit Free Press, it's unclear how much, if anything, they were able to do in the city.
That said, considering that the movie takes place 50 years ago during a riot that burned down buildings and destroyed city streets, shooting in modern-day Detroit might not have lent the film any more authenticity. Furthermore, the fact that Detroit was not actually shot in Detroit is also forgivable when you consider the main set piece of the film: the annex of the Algiers Motel, where roughly a dozen black men and two white women were held captive by local police. The narrative focuses on the police and their victims, who spent hours being beaten and psychologically tormented. The event resulted in the deaths of three black men, each of whom was left unceremoniously in the Motel annex by their shooters.
The real Algiers Motel was torn down in the 1970s, so Bigelow and her crew would have had to build a set for the film regardless of where Detroit was filmed. In the end, they chose a house in Dorchester as their Annex. "Basically my production designer took over the house and transformed it into the Algiers Motel annex," Bigelow explained to The Boston Globe.
In the end, where Detroit was filmed doesn't matter nearly as much as the content of the actual finished product. Instead of asking where Detroit was filmed, it might be better to ask how close Detroit is to the truth.