States with the death penalty have consistently had higher murder rates than states without the death penalty. If the death penalty was acting as a deterrent to murder, one might expect that the gap between these two groups would lessen over a long period of time as states using the death penalty obtained an advantage in reducing murders. However, the gap has grown larger over the past 18 years. In 2007, states with the death penalty had a 42% higher murder rate than states without the death penalty. In 1990, the gap was only 4%.

A murder rate is obtained by dividing the number of murders in a state by the state’s population. It is possible to obtain a single murder rate for “states with the death penalty” by adding the total number of murders in such states by the total population of these states. A murder rate for “states without the death penalty” can be similarly obtained. To see the results of these calculations for each year 1990-2007, click here. In 2007, the murder rate for states with the death penalty was 5.83 and for states without the death penalty it was 4.10, a 42% difference. The national murder rate in 2007 was 5.6.

(Murder rates from FBI Uniform Crime Report, calculations by David Cooper; DPIC, Nov. 25, 2008). See Deterrence.