John Radzilowski provides an interesting argument in the Journal of American Ethnic History that the United States saw a baby boom amongst immigrants in the 1920s. He suggests that you can see this having an effect in all parts of American history- for instance in some Polish parishes in 1941 40% of the congregation went to fight in World War Two. Radzilowski doesn't suggest many implications- some are obvious though. The American migration of southern and eastern Europeans was so large and over so quickly that its impact is not really a good indicator of what other immigrant populations will do. Secondly this immigrant community and in particular its brief and important baby boom in the twenties changed American history- a huge generation of young people in the thirties emerging from labouring working classes in the midst of the depression helps explains the rise in crime in the thirties. Its possible there are other conclusions that might be drawn but Radzilowski draws attention to an interesting demographic phenomenon.