Solitary Confinement and the U.S. Prison Boom

Solitary confinement is a harsh form of custody involving isolation from the general prison population and highly restricted access to visitation and programs. Using detailed prison records covering three decades of confinement practices in Kansas, we find solitary confinement is a normal event during imprisonment. Long stays in solitary confinement were rare in the late 1980s with no detectable racial disparities, but a sharp increase in capacity after a new prison opening began an era of long-term isolation most heavily affecting Black young adults. A decomposition analysis indicates that increases in the length of stay in solitary confinement almost entirely explain growth in the proportion of people held in solitary confinement. Our results provide new evidence of increasingly harsh prison conditions and disparities that unfolded during the prison boom.