How were female surnames historically recorded in the US Census?


I am interested in studying the naming practices historically in the US. One aspect I am interested in is how often married women took the surname of their partners, or kept their original surnames.

One concern is that the surname of wives were simply assumed to be that of the household head (and not directly asked). Does anyone have any information on how surnames were typically recorded in the historical US censuses (1850-1940)? Or would know any resources that might give more insight into this?

I recommend reviewing the enumerator instructions available on the Questionnaires page on IPUMS USA as a place to start. For example, in 1930 the instructions state to “enter the name of every person” with the “'last name or surname, then the given name in full”. However, “where the surname is the same as that of the person on the preceding line do not repeat the name, but draw a horizontal line (-) under the name above.” Based on these instructions, enumerators were supposed to ask for each person’s surname, but only record it if it differed from the surname of the preceding individual. It’s conceivable that enumerators could have skipped asking for the wife’s surname, especially given how superfluous such a question might have seemed given prevailing norms around women taking their husband’s surname upon marriage. However, I’m unable to find any resources that give a sense of just how common this type of error was.