Leah's younger sisters Kate and Margaret reported mysterious rapping sounds at the family home in Hydesville, New York, sparking the Spiritualist movement that Leah would later organize and promote.
On the night of March 31, 1848, in a small frame house in Hydesville, New York, Leah Fox's younger sisters Kate (age 11) and Margaret (age 14) claimed to communicate with the spirit of a murdered peddler through a series of mysterious rapping noises. Though Leah, then a mature woman in her thirties living separately in Rochester, was not present for the initial event, she quickly became the central architect of what would follow.
Upon learning of the phenomena, Leah brought her sisters to live with her in Rochester and began organizing public demonstrations, effectively becoming their manager and the driving business force behind their emerging fame. She arranged sittings, charged admission, and helped codify the practice of the 'séance' as a structured, repeatable public event.
This moment is historically significant as the founding event of Modern Spiritualism, a religious and social movement that would attract millions of adherents across the United States and Europe, including prominent intellectuals, reformers, and eventually even public figures such as Mary Todd Lincoln. Leah's entrepreneurial instincts transformed a local curiosity into a national phenomenon, and she is often credited as the true founder of organized Spiritualism as a movement, distinct from her younger sisters who were merely its initial mediums.