I think I stumbled on an interesting bit of bureaucratic history today. In trying to help a relative decipher a 1910 census listing for a Fanny Cohen in New York City. The census form is confusing, apparently because it was worked over two or three times. The initial listing showed her and her parents as being born in Russia, and Yiddish was her first language.
The confusing parts were additional notations, possibly made by the census taker, but more likely done later. The notes aren't clear. Our best interpretation at the moment is that they are classifications perhaps required by the Immigration Act of 1924, that is, what was "Russia" in 1910 becomes Poland or Lithuania after WWI. Because the Act imposed quotas based on the national origins of those already in America, the Census bureau seems to have had to come up with those statistics.
I'm curious whether this is true, and if so how they went about it. If you have someone going over the 1910 census in 1924, how do they know which part of the Russian Empire, now defunct, Fanny Cohen came from?