A recent paper published on October 13, 2017 by Walter Enders, Paul Pecorino, and Ann-Charlotte Souto of the University of Alabama looks at Racial Disparity in U.S. Imprisonment Across States over Time. The paper’s abstract desribes its focus and conclusions:
The overall incarceration rate in the United States is extremely high by international standards. Moreover, there are large racial disparities, with the black male rate of imprisonment being 5.5 times the white male rate in 2014. This paper focus on how this black-white imprisonment ratio has behaved over time within and across states. We show that the large increase in black imprisonment between 1978 and 1999 was driven by increases in the overall rate of imprisonment, while the smaller decrease which occurred between 1999 and 2014 was driven by reductions in the black-white ratio. For many states, the black-white ratio turned upward in the mid-1980s, where this upturn may have been linked to the crack epidemic. Many states experienced a downturn in the black-white ratio starting in the 1990s. Whatever its other effects, this suggests that the 1994 crime bill did not aggravate the preexisting racial disparity in imprisonment. California’s experience has been strongly counter to national trends with a large increase in the racial disparity beginning in the early 1990s and continuing until near the end of our sample.