Ammo for the census debate. I have read through every questionnaire since 1960 and have found only two that do not ask questions about citizenship (those being 1960 and 2010).

https:// www.census.gov/history/www/through_the_decades/questionnaires/

1970 - Page 6 question `6.

1980 - Page 6 question 12.

1990 - Page 6 question 9.

2000 - Page 3 question 15.