WASHINGTON (CNN) - An internal Census Bureau memo sent to Commerce Secretary Wilbur Ross warns that adding a citizenship question to the 2020 Census will hurt "the quality of the census count" and be "very costly."
The memo was made public on Saturday by Democrats on the House Committee on Oversight and Government Reform after the Department of Commerce provided the committee with documents related to a controversial move announced in March to include a citizenship question as part of the 2020 Census.
Census data serves as the basis for decisions about how to allocate federal resources and how congressional districts are drawn. The purpose of collecting the data is to count the entire US population, not just citizens.
Critics who oppose the addition of a citizenship question fear that asking about citizenship status will lead to an inaccurate population count if undocumented individuals decline to complete the questionnaire.
The internal memo dated January 19, 2018, to Secretary Ross from John Abowd, the Census Bureau's chief scientist and associate director for research and methodology, warns of a variety of risks associated with asking about citizenship.
It states that adding a citizenship question would prove to be "very costly, harms the quality of the census count, and would use substantially less accurate citizenship status data than are available from administrative sources." In a chart comparing various alternatives, the memo states that adding a citizenship question would result in "major potential quality and cost disruptions" to the 2020 Census.
The memo notes that a potential advantage of adding the question is that it would provide a "direct measure of self-reported citizenship for the whole population."
But the memo lists more shortcomings than advantages associated with asking about citizenship, saying that the downsides would include the fact that "citizenship status is misreported at a very high rate for non-citizens."
The Commerce Department has said it is adding the citizenship question to the 2020 Census at the request of the Justice Department to improve enforcement of the Voting Rights Act.
In a statement on the memo, Maryland Rep. Elijah Cummings, the top Democrat on the House oversight committee, said "this limited document production reveals that the Trump Administration overruled the warnings of career experts at the Census Bureau, and now we need to know why."
The Department of Commerce did not immediately respond to a request for comment on the memo.
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