We aren't talking about the 2010 census you dishonest dumbfuck. We are talking about the 2000 census. And yes 18 million Americans received it and it did contain the question of whether one was a US citizen.
The statement that this question has not been asked since 1950 is therefore, a flat out lie no matter how much you attempt to move those goalposts.
The Census Long Form was sent to only 18 million lucky households–a small sample of the 105.5 million households in the US in 2000.
http://blog.cubitplanning.com/2010/09/census-2010-long-form/
And wrong again, this getting to be a habit with you, and the 2000 short form has only six questions
https://www.census.gov/dmd/www/pdf/d61a.pdf