As early as 1900, the US Census was asking people about where they were born and when they had arrived in the US. Using these markers, as well as other data points such as homeownership, marital status, and citizenship, Vigdor created an index that calculated a statistical difference between immigrants and native-born Americans. Full assimilation, according to Vigdor's work, is when these data points are indistinguishable.
"Assimilation is a process whereby people come to adopt the various mannerisms and behavior of native-born residents of a country...," Vigdor says. "By being able to track immigrants as they spend more time in the US, we can trace out how that process works. And the process actually works in a remarkably similar manner whether you're looking over the past 20 years in the US or looking at immigration from Eastern Europe at the turn of the last century."
In other words, a first-generation immigrant will usually struggle with more cultural differences than his American-born child, who will grapple with more cultural disconnect than his children.
But there are also significant differences between immigrant groups, he points out, more so than between immigrants overall and the native-born population.
In his work, he developed three categories of assimilation – civic, cultural, and economic – and then combined those categories for an overall assimilation score. By his findings, Latino immigrants tend to be least assimilated, particularly on measures of civic and economic assimilation, which include characteristics such as citizenship, professional status, and homeownership.