President Trump on Thursday said he had instructed the Department of Commerce to "immediately begin work on a new and highly accurate" census that would exclude undocumented immigrants .

But the census is a massive undertaking and has huge repercussions nationally, including on congressional seat alignment — so it's not something that can be changed quickly. In fact, the Census Bureau said it began planning the 2030 census in 2019.

Asked for comment on Mr. Trump's post, a Commerce Department spokesperson told CBS News in a statement: "The Census Bureau will immediately adopt modern technology tools for use in the Census to better understand our robust Census data. We will accurately analyze the data to reflect the number of legal residents in the United States."

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