By linking data on Ellis Island arrivals with the 1940 US Census Zach Ward and I estimate the effect of age at arrival for immigrant outcomes in the US. Using within-family variation, Zach and I find that arriving at an older age, or having more childhood exposure to the European environment, led to a larger negative wage gap compared to the native born. Those who arrived as infants had no income gap relative to natives, in contrast to those who arrived as teenagers. Therefore, a key determinant of immigrant outcomes during the Age of Mass Migration was the country of residence during critical periods of childhood development.
This paper is forthcoming at The Journal of Economic History. The working paper version is available here.