For decades it has been an unspoken secret known but not talked about, not possible to forget but easier not to mention.
It may even have inspired a world-famous, local-born songwriter in one of his strongest, darkest works.
The secret is captured on a hazy photograph. It shows three black men being hanged from a lamp-post while the lynch mob stands around smiling. Then, almost unbelievably, the locals in Duluth, Minnesota, turned it into a postcard.
The singer was Bob Dylan, who was born in Duluth in 1941, before his family moved to nearby Hibbing. Twenty-five years later, 'Desolation Row' one of his most celebrated songs, began "They're selling postcards of the hanging..."
This week, eight decades on from the event, the town has been remembering the incident not so much to point the finger of guilt but in order to try and heal the painful memories.
Duluth's mayor Gary Doty, said he initially had doubts about the week of remembrance that has included a march, fund-raising for a memorial sculpture and a series of readings by a local author, Michael Fedo, who wrote a book about the lynching.
"When [the organisers] first came to me I thought 'Why would I want to tell the world something so horrible happened in my city," said Mr Doty.
"Race relations in this city are good. But then you are talking to a white, middle-aged guy, so there must be some things we need to work on." The lynching took place almost precisely 81 years ago, on 15 June 1920, when a mob of hundreds of white men pulled six black men from the city's jail and hanged three of them.
The men members of the John Robinson Show Circus were accused by a white teenager of raping his girlfriend and forcing him to watch. It was a lie but the men were arrested.
Outside the jail an angry mob gathered, broke in and dragged the men to the intersection of First Street and Second Avenue East where they were hanged. Then someone took the photo that was turned into a postcard.
Last Friday, more than 100 people walked the route that the lynch mob took, pausing in silence for three minutes outside the old police station, from which the men were taken.
Across the street is the office of Crawford Funeral Service, the undertakers traditionally used by the black community. The owner James Crawford was the only person who would take in the bodies of the three hanged men Elias Clayton, Elmer Jackson and Issac McGhie and ensure they received a proper burial.
Now his great-granddaughter Joan Crawford, can look out from her office window to where the men were hanged. "It makes you embarrassed to be a white person," she said.
Portia Johnson, one of the organisers of this week of remembrance, said the lynching had always divided the community. Many chose not to acknowledge it, refusing to accept that one of those smiling faces may belong to their grandfather.
Many refused to talk about it because "in this part of the country, they never thought it could happen". She added: "There's other ways of 'lynching' folks. Like no jobs, like the number of blacks in jail disproportionate to society."
And while Duluth only has a small black population, the legacy of racism persisted long after the lynching. Resident Howard Taylor, 74, said he was warned more than 50 years ago about moving there because of its reputation. Mr Taylor, who moved from the South to escape racism, said there was still a lack of understanding. " I hope this opens the eyes of some people."
Either that or it's as Bob Dylan wrote: "Someone says, 'You're in the wrong place, my friend, you better leave'."Reuse content