"Changes in the incarceration rates for men and women by race were associated with changes to the overall composition of the custody population at midyear 2007. Black men had an incarceration rate of 4,618 per 100,000 U.S. residents at midyear 2007, down from 4,777 at midyear 2000. For white men, the midyear 2007 incarceration rate was 773 per 100,000 U.S. residents, up from 683 at midyear 2000. The ratio of the incarceration rates of black men to white men declined from 7 to 6 during this period.

"Changes in the incarceration rates for women were more distinct. At midyear 2000, black women were incarcerated at a rate 6 times that of white women (or 380 per 100,000 U.S. residents versus 63 per 100,000 U.S. residents). By June 30, 2007, the incarceration rate for black women declined to 3.7 times that of white women (or 348 versus 95). An 8.4% decline in the incarceration rate for black women and a 51% increase in the rate for white women accounted for the overall decrease in the incarceration rate of black women relative to white women at midyear 2007."

Source

Sabol, William J., PhD, and Couture, Heather, Bureau of Justice Statistics, Prison Inmates at Midyear 2007 (Washington, DC: US Department of Justice, June 2008), NCJ221944, p. 8.
http://www.bjs.gov/content/pu…