It was an article in Salon by Glenn Greenwald. Link here:
http://www.salon.com/opinion/greenwald/2009/03/28/webb/... DU discussion on the article here:
http://www.democraticunderground.com/discuss/duboard.ph... The article was more about US incarceration vs. the rest of the world, but it did mention the extraordinary incarceration figures for blacks. Excerpt:
"African-Americans are about 12% of our population; contrary to a lot of thought and rhetoric, their drug use rate in terms of frequent drug use rate is about the same as all other elements of our society, about 14%. But they end up being 37% of those arrested on drug charges, 59% of those convicted, and 74% of those sentenced to prison by the numbers that have been provided by us. . . ."