The 1920 Wall Street Bombing: America's Deadliest Unsolved Terror Attack Explained

On a warm September afternoon in 1920, the busiest corner of American finance turned into a scene of chaos in the span of a few seconds. It happened without warning, without a claimed motive, and without ever being solved. More than a century later, it remains one of the strangest unresolved mysteries in United States history.

An Ordinary Lunch Hour

September 16, 1920, started out like any other Thursday on Wall Street. The lunchtime crowd was thick with clerks, stenographers, messengers, and bankers spilling out of their offices for a midday break. The corner of Wall and Broad Streets was, at the time, the financial heart of the entire country. J.P. Morgan and Company, arguably the most powerful bank on earth at that point, sat right there. Just across the way stood the US Sub-Treasury Building, and the New York Stock Exchange was only a short walk down the block.

At exactly 12:01 p.m., as the bells of nearby Trinity Church rang out for noon, a horse-drawn cart rolled up and parked along the curb outside the Morgan building. Nobody paid it much attention. Delivery carts were a completely normal sight in that part of the city.

Then it detonated.

A Bomb Built to Maim

Investigators later determined the wagon had been packed with roughly 100 pounds of dynamite. But the dynamite itself wasn't what made the attack so devastating. Whoever built the device had surrounded the explosives with about 500 pounds of heavy, cast-iron window weights — ordinary hardware store items on their own, but when packed tightly around a timed explosive, they turned into a burst of jagged shrapnel that tore through the crowd for a full city block in every direction.

The blast shattered windows a dozen stories up. It flipped cars over, knocked streetcars off their rails two blocks away, and left craters and scorch marks across the stone facades of nearby buildings. Some of those marks, remarkably, are still visible today on the exterior wall of 23 Wall Street.

By the time the smoke cleared, 30 people were dead. Eight more would later die from their injuries, bringing the final toll to 38. Hundreds more were hurt, many badly burned or cut by flying glass and metal fragments. At the time, it stood as the deadliest act of terrorism ever carried out on American soil, a grim record it would hold for 75 years, until the 1995 Oklahoma City bombing surpassed it.

Who Actually Got Hurt

One of the more haunting details from that day is who ended up among the victims. The obvious assumption would be that the attackers were targeting Morgan executives or Wall Street's wealthiest players. But most of the dead and wounded weren't bankers or financiers at all. They were young clerks, secretaries, and errand runners — ordinary working people who simply happened to be walking past at the wrong moment. A future American icon was even caught up in the chaos: Joseph P. Kennedy, then a young stockbroker and later the father of President John F. Kennedy, was reportedly knocked off his feet by the force of the blast.

A City in Shock, a Market That Refused to Blink

What happened next says almost as much about the American mindset of the era as the bombing itself. Rather than shutting down out of fear, Wall Street doubled down on its own reputation for resilience. The New York Stock Exchange opened right on schedule the very next morning. Trading resumed as though nothing had happened, and within days, financial commentators were already writing about renewed confidence in the markets. The message, whether intentional or not, came through clearly: nothing — not even mass casualties in the heart of the Financial District — would be allowed to interrupt business as usual.

City officials moved quickly to clean up the physical damage too, in some cases before investigators had even finished collecting evidence. Debris was cleared, streets were reopened, and the crime scene was essentially erased within days. That decision would go on to haunt investigators for decades afterward.

A Case That Went Nowhere

Despite an enormous investigation involving city police, the fledgling Bureau of Investigation (the agency that would later become the FBI), and even private detectives hired by J.P. Morgan and Co. itself, no one was ever arrested or formally charged for the bombing.

Early theories focused heavily on anarchist and radical political groups, which were a genuine and active presence in the United States at the time. Suspicion quickly landed on a network known as the Galleanists, followers of Italian anarchist Luigi Galleani, who had already been linked to a wave of bombings across the country the previous year. Some historians believe the Wall Street attack may have been retaliation for the recent arrests of Sacco and Vanzetti, two Italian anarchists whose case had become a national flashpoint, or for the government's aggressive deportation campaign targeting foreign-born radicals during that period.

One name that keeps surfacing again and again in the historical record is Mario Buda, also known as Mike Boda — a known associate of Sacco and Vanzetti with a documented history of building explosives. Buda fled the United States for Italy not long after the bombing and was never extradited or formally questioned about it. Investigators strongly suspected his involvement, but suspicion alone was never enough to secure a conviction, or even confirm a motive.

By 1940, roughly two decades after the attack, federal investigators reopened their old files one more time. Their internal conclusion, based on years of scattered evidence, leaned toward the theory that Italian anarchists or associated radicals were behind the blast. But by then, the trail had gone cold, key witnesses had died or disappeared, and no formal charges were ever filed. The case was ultimately closed without resolution.

Why It's Still Remembered

The Wall Street bombing helped shape the early career of a young Justice Department official named J. Edgar Hoover, who used the case, along with the broader "Red Scare" panic of the era, to argue for expanded federal surveillance and investigative powers. In many ways, the bombing became a turning point in how the US government approached domestic terrorism and political extremism, long before those terms were part of everyday vocabulary.

Today, the event has largely faded from public memory, overshadowed by the scale of more recent tragedies. Yet it remains a striking historical parallel: a sudden, unexplained act of violence in the middle of America's financial capital, followed by a country that chose to move forward without ever fully understanding what had happened or why.

The scars on the wall of 23 Wall Street are still there if you know where to look — small, unassuming reminders of one of the most violent and least understood mornings in the history of the American financial system.

A Mystery That Outlived Everyone Involved

Perhaps what makes this story so unusual, even by the standards of unsolved crimes, is how quietly it disappeared from public conversation. There was no trial to follow, no dramatic manhunt that captured headlines for years, no clear villain for the public to direct its anger toward. Instead, the case simply faded, year after year, as the officials who worked it retired or passed away, and the physical evidence, cleared from the streets within days of the blast, was long gone before anyone realized how important it might have been.

Historians who have revisited the case in the decades since generally agree on the broad outline: a politically motivated act, almost certainly tied to the anarchist movements of the era, carried out by people skilled enough to build a devastating device but careful enough to leave behind almost nothing that could identify them. Beyond that, much of what remains is guesswork pieced together from fragments — old surveillance reports, immigration records, and the recollections of people who were never entirely sure what they had witnessed.

For a country that would go on to face far larger and more thoroughly documented attacks in the century that followed, the Wall Street bombing stands out as a strange kind of first chapter — a moment that shocked the nation, reshaped how it thought about domestic security, and then quietly slipped into the background of American memory, waiting for each new generation to rediscover it.