DAVID TERESHCHUK, SPECIAL CORRESPONDENT, PHILADELPHIA, PA:

America's use of solitary confinement in effect started here at Eastern State Penitentiary of Pennsylvania in 1829. A British architect won a $100 for his design. And the basic operating principle was that solitude would enable prisoners to get regretful and "penitent" about their crime – hence the word "Penitentiary".

Against a background of grim prison conditions, Pennsylvania's early 19th-century Quakers saw introducing solitary confinement as a way to reform.