Immigration and African-American Employment Opportunities: The Response of Wages, Employment, and Incarceration to Labor Supply Shocks

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 4.0 percent, lowered the employment rate of black men by 3.5 percentage points, and increased the incarceration rate of blacks by almost a full percentage point.

Substitution Between Immigrants, Natives, and Skill Groups

The wage impact of immigration depends crucially on the elasticity of substitution between similarly skilled immigrants and natives and the elasticity of substitution between high school dropouts and graduates. This paper revisits the estimation of these elasticities. The U.S. data indicate that equally skilled immigrants and natives are perfect substitutes. The value of the second elasticity depends on how one controls for changes in demand that have differentially affected high school dropouts and graduates. The groups are imperfect substitutes under standard trend assumptions, but even slight deviations from these assumptions can lead to an outright rejection of the CES framework.

Imperfect Substitution between Immigrants and Natives: A Reappraisal

In a recent paper, Ottaviano and Peri (2007a) report evidence that immigrant and native workers are not perfect substitutes within narrowly defined skill groups. The resulting complementarities have important policy implications because immigration may then raise the wage of many native-born workers. We examine the Ottaviano-Peri empirical exercise and show that their finding of imperfect substitution is fragile and depends on the way the sample of working persons is constructed. There is a great deal of heterogeneity in labor market attachment among workers and the finding of imperfect substitution disappears once the analysis adjusts for such heterogeneity. As an example, the finding of immigrant-native complementarity evaporates simply by removing high school students from the data (under the Ottaviano and Peri classification, currently enrolled high school juniors and seniors are included among high school dropouts, which substantially increases the counts of young low-skilled workers ). More generally, we cannot reject the hypothesis that comparably skilled immigrant and native workers are perfect substitutes once the empirical exercise uses standard methods to carefully construct the variables representing factor prices and factor supplies.

Effects of epitaxial strain on the growth mechanism of YBa2Cu3O7-x thin films in [YBa2Cu3O7-x / PrBa2Cu3O7-x] superlattices

We report on the growth mechanism of YBa2Cu3O7-x (YBCO). Our study is based on the analysis of ultrathin, YBa2Cu3O7-x layers in c-axis oriented YBa2Cu3O7-x / PrBa2Cu3O7-x superlattices. We have found that the release of epitaxial strain in very thin YBCO layers triggers a change in the dimensionality of the growth mode. Ultrathin, epitaxially strained, YBCO layers with thickness below 3 unit cells grow in a block by block two dimensional mode coherent over large lateral distances. Meanwhile, when thickness increases, and the strain relaxes, layer growth turns into three dimensional, resulting in rougher layers and interfaces.Comment: 10 pages + 9 figures, accepted in Phys. Rev.