On December 31, 1982, there were 42,915 more inmates under the jurisdiction of State and Federal prisons than the year before, the largest 1-year increase in history. This 11.6 percent increase brought the Nation's prison population to 412,303. When added to last year's record 12.5 percent growth, it caps a remarkable surge in imprisonment in the past decade. The Nation as a whole has more then doubled its prison population in that time; several States have tripled theirs. The West's 17.7 percent increase last year led the Nation, compared with 12.9 percent for the South, 10.6 percent for the Northeast, and 7.2 percent for the North Central States. Observers attribute the West's surge to several factors: population increases, particularly of transient young males; increased ethnic conflict; and a sharp turn from a liberal to a conservative political outlook in States like California, Washington, and Oregon. Overall, the prison population increase has been attributed to demographics (the postwar baby 'boom') and an increasingly punitive public attitude. Because the cost of housing the growing inmate population under humane conditions is prohibitive, States have sought to deal with the problem through emergency early release measures for nonviolent offenders (Michigan) and sentencing guidelines that reduce the use of imprisonment (Minnesota). Diversion programs have generally not impacted prison populations, since they are used most often with persons who would not have otherwise been sent to prison. The experts agree that unless some dramatic and unexpected event occurs, there will be no improvement in prison overcrowding in the next few years.