This paper examines the evolution of immigrant earnings in the United States between 1970 and 2010. There are cohort effects not only in wage levels, with more recent cohorts having lower entry wages through 1990, but also in the rate of wage growth, with more recent cohorts experiencing less economic assimilation. The slowdown in assimilation is partly related to a concurrent decline in the rate at which the new immigrants add to their human capital stock, as measured by English language proficiency. The data also suggest that larger national origin groups experience less economic assimilation
Borjas, George J. "The Slowdown in the Economic Assimilation of Immigrants: Aging and Cohort Effects Revisited Again." Journal of Human Capital 9.4 (Winter 2015): 483-517.