Missouri: Out of Purgatory

On the high bluffs overlooking the Missouri River, golfers in Bermuda shorts and T shirts queue up to play an intricate, 18-hole miniature course. Near by, tables buzz with games of checkers and pinochle. From handball courts comes the hollow thunk of ball against board. The country-club atmosphere is deceptive—and was planned that way as part of a wall-to-wall overhaul that in two years has transformed the Missouri State Penitentiary at Jefferson City from what a visitor once termed a "loathsome stone purgatory" into one of the nation's model prisons.

For most of its 132 years, the Missouri poky resembled a...