New research on immigration. This is the first study to look for a link between immigration and incarceration rates in the black population:
Immigration and African-American Employment Opportunities: The Response of Wages, Employment, and Incarceration to Labor Supply Shocks, by George J. Borjas, Jeffrey Grogger, and Gordon H. Hanson, NBER WP 12518: Abstract The employment rate of black men, and particularly of low-skill black men, fell precipitously from 1960 to 2000. At the same time, the incarceration rate of black men rose markedly. This paper examines the relation between immigration and these trends in black employment and incarceration. Using data drawn from the 1960-2000 U.S. Censuses, we find a strong correlation between immigration, black wages, black employment rates, and black incarceration rates. As immigrants disproportionately increased the supply of workers in a particular skill group, the wage of black workers in that group fell, the employment rate declined, and the incarceration rate rose. Our analysis suggests that a 10-percent immigrant-induced increase in the supply of a particular skill group reduced the black wage by 3.6 percent, lowered the employment rate of black men by 2.4 percentage points, and increased the incarceration rate of blacks by almost a full percentage point. [open link]
I think it's important to add this from the end of the introduction:
These findings can obviously generate a great deal of controversy in the immigration debate and can be easily misinterpreted. As a result, we are extremely cautious in both the presentation and interpretation of the evidence. Although we have attempted to control for other factors that may account for the large shifts in black employment and incarceration rates over the four-decade period that we examine, it should be obvious that no study can control for all possible factors. It is equally important to emphasize that although the evidence suggests that immigration played a role in generating these trends, most of the decline in employment or increase in incarceration in the black population remains unexplained. Put differently, immigration seems to have an effect and this effect seems to be numerically important, but we would have witnessed much of the decline in black employment and the concurrent increase in black incarceration rates even if there had been no immigration in the past few decades.