On September 16, 1920, the "Wall Street bombing" occurred at 12:01 when a horse-drawn wagon exploded on Wall Street, New York, killing 38 and injuring 143. An excerpt from the article:
"Based on bomb attacks over the previous decade, the Bureau initially suspected followers of the Italian Anarchist Luigi Galleani. But the case couldn’t be proved, and the anarchist had fled the country. Over the next three years, hot leads turned cold and promising trails turned into dead ends. In the end, the bombers were not identified. The best evidence and analysis since that fateful day of September 16, 1920, suggests that the Bureau’s initial thought was correct—that a small group of Italian Anarchists were to blame. But the mystery remains.
For the young Bureau, the bombing became one of our earliest terrorism cases—and not the last, unfortunately, to involve the city of New York. As the decades passed, the threat from terrorism would grow and change, with different actors and causes coming and going from the scene.
The book, Hopeless Cases: The Hunt for the Red Scare Terrorist Bombers by Charles H. McCormick, University Press of America: New York, 2005, and the FBI investigative file on the case were used in the development of this article."