by Morgan Reynolds

About the author: Morgan Reynolds is director of the Criminal Justice Center of the National Center for Policy Analysis, a nonprofit public policy think tank. He is also a professor of economics at Texas A&M University.

Prisons have broken the back of our 35-year crime wave. It’s about that simple.

An estimated 1.8 million inmates were in prisons and jails at midyear 1998— double the number behind bars a decade earlier. A Justice Department study finds that the average time spent by violent criminals in state prisons rose to 49 months in 1997 from only 43 months in 1993. Prison growth has begun to moderate, however, with 1998’s 4.4 percent increase below the average 6.2 percent increase in the 1990s.

Lo and behold, as prisons filled, crime fell. The FBI’s crime index has declined for seven straight...