Listen and subscribe to our podcast: Via Apple Podcasts | Spotify | Stitcher

Neighborhood forums are awash in reports of unusual noises like fireworks and gunshots. But something more mysterious has been pestering the residents of Minneapolis' Longfellow area.

For several decades, people living near the Mississippi River in south Minneapolis have reported hearing what's become known as the "Longfellow Boom." Some describe it as a "house-shakingly loud" booming or crashing noise that seems to only happen at night during the summer months.

Max Nesterak, deputy editor of the Minnesota Reformer publication, is one of many area residents searching for the cause of the racket. His theory is that the boom "might have something to do with the river." But after fruitless research, he reached out to Curious Minnesota, the Star Tribune's community-driven series fueled by reader questions.

The sound has been so persistent over the years that the city's Police Department, Health Department and City Council members have all put their ear to the ground trying to figure out what is going on — to no avail. It even drew the scrutiny of the FBI in the run-up to the Republican National Convention in 2008.

Boom theories abound among neighbors, who speculate that it could be exploding electrical transformers, sewer issues, fireworks, freight trains, or even a fault line on the Mississippi River. Others joke that it's the work of extraterrestrials. (Please send your ideas to

"There was one night — like 4 in the morning — where I was shaken awake by [a boom] so, so loud, it was shaking the window panes," said Julie Rand, who has lived in the area for more than a decade. "It was a kind of thing where I was sure an explosion happened like just across the street. ... I just was sure that somebody's boiler blew up, and that their house was gonna be on fire or something."

Rand said she has heard the noise 10 to 12 times. She described it as a "low, loud booming noise ... like something crashed," but different from a gunshot or a car crash.

Sound sleuthing

Plenty of work has gone into rooting out the source of this phenomenon.

Minneapolis City Council Member Andrew Johnson, who represents the southeastern corner of the city, said he was part of a project to triangulate the location of the boom via aircraft noise sensors and towers at MSP Airport. Despite the precise machinery, he said they never found the location of the noise — which has been reported to come from different places at times.

"This has been going on long enough, you would think ... that somebody would still have seen something," Johnson said. "Given the number of times that this has happened over the years, you still think you'd have a speeding car going away. Or somebody would say, 'Hey, I saw the flash right out my window,' or that sort of thing. But to the best of my knowledge, that hasn't happened."

Noise problems are under the purview of the city's Health Department. The agency has received and investigated multiple calls about the boom in the past without success, said Patrick Hanlon, director of the department's environmental programs. No one has called them about it in the last five years.

"We deal with a lot of noise issues, and we just could not figure out what [the boom] was," Hanlon said.

The Minneapolis Police Department has investigated the boom several times. MPD spokesman Garrett Parten said they have no updates on what might be causing it.

A spokeswoman for Xcel Energy, Lacey Nygard, said that while they aren't sure what has caused booms over the years, they are not "aware of any outages or impacts to Xcel Energy equipment when they have occurred."

Former Star Tribune columnist Jon Tevlin and ballistics expert William Gurstelle spent a night in the summer of 2010 roaming around the area looking for the cause. At the time, Gurstelle called the sewer gas theory "not probable," and ruled out sonic booms and anarchists. He later said he thought the booms were not related, but "people love to be part of the mystery, and so they link the booms."

The interest surrounding the boom is kept alive in online forums, like Twitter, Reddit, NextDoor and E-Democracy. There, neighbors periodically come together in comment threads to discuss their thoughts on the boom and what it could be.

A local expert

Fiona Quick, a writer who has lived in the Longfellow area for most of her life, has been meticulously documenting the phenomenon since she returned to the neighborhood to help care for her mother in 2008.

In 2010, she compiled her research into one thorough blogpost and has since been a reliable Twitter presence anytime the booms occur.

Quick's theories mostly involve human activity, such as improvised explosives, people throwing firecrackers in the water to catch fish or people just generally "being stupid by the river." Her lead theory, however, is that there are many causes and their proximity to the river is making the sounds louder.

"Because you're down by the river, the sound echoes inordinately," she said. "Where I live is in a built-in kind of swampy area where ... the sound moves and the ground is kind of a built-in spring. So everything is river-based, water-based and the sound travels differently."

If you'd like to submit a Curious Minnesota question, fill out the form below:

This form requires JavaScript to complete.

Read more Curious Minnesota stories:

Are motorcycles allowed to be louder than cars in Minnesota?

Is it legal to panhandle in the median of Minneapolis streets?

Why does Minneapolis keep planting trees under power lines?

How did Minneapolis end up with a street named after Xerxes, a Persian king?

Why did Minneapolis tear down its biggest train station?

Why is there a new cellular pole in my Minneapolis neighborhood?