A new study sponsored by the Manhattan Institute, a New York-based think tank, shows that immigrants of the past 25 years have assimilated in the U.S. at a much faster rate than immigrants of previous generations. According to the report, current immigrants come to the U.S. with less ability to speak English and lower earning power than their immigrant forbearers, take on native-born traits at a greater speed than seen previously.

The study, which measured assimilation by investigating rates of U.S. citizenship and military service, economic factors such as salary rates and home ownership, and cultural factors such as the ability to speak English and intermarrying rates, shows that the level of immigration has consistently increased, with a distinct raise in assimilation rates seen since the early 1990s.

Study investigators purport that this increase in assimilation rates may be due to the economic expansion of the 1990s that created more job opportunities at all economic levels. Many new immigrants started economically at a very low level, enabling a faster increase in assimilation as they improved their personal economies. However, the investigators do note that assimilation rates seen in ethnic populations with high levels of undocumented residents, such as Mexicans, are much lower than those of ethnic populations with lower levels of undocumented residents; this, the investigators state, is most likely due to the fact that a large portion of the ways to assimilate are cut off and unavailable to those that are in the country illegally.