More than 122,000 people are imprisoned in solitary confinement across the US's multi-layered jails and prisons systems, according to research published Tuesday.

Exact figures have long been difficult to determine, in part, because of the US's multi-jurisdiction imprisonment systems that see tribal, local, state and federal governments each running parallel networks. There is no single authority that collects the total, making it hard to develop a clear picture of the situation.

But Solitary Watch, an advocacy group and watchdog, released a landmark report with fellow advocacy group Unlock the Box cataloging 122,840 imprisoned daily in solitary detention across the nation in 2019, the most recent data available from the Bureau of Justice Statistics (BJS)

The snapshot figure includes people placed in solitary for 22 hours or more per day, and does not include those held in solitary in immigrant or juvenile facilities. The report's authors emphasize that the tally is likely undercounting the true total, in part because it relies on self-reported data from correctional facilities.

The tally is based on data from the BJS, state prison systems information not included in the bureau's reporting, and a survey of local jails conducted by the Vera Institute of Justice.

“The widespread use of solitary confinement in our prisons and jails is a humanitarian crisis. As the United Nations has confirmed, it’s torture taking place on U.S. soil. Yet until now, we haven’t even had a comprehensive count of how many people are in solitary,” Jean Casella, Solitary Watch director, said in a statement accompanying the report's release.

“This kind of full and accurate information is critical to creating accountability and bringing about change,” added Casella.

The report's tally of 122,840 inmates in solitary comprises just over 6% of the total incarcerated population in the US. (Anadolu Agency)