It is illegal for the Census Bureau or any of its employees to share your personal information with any other government agency. No court of law, not even the President of the United States, can access your individual responses. Your answers are protected by law (Title 13 of the U.S. Code, Section 9) and are strictly confidential.An interesting story...
In 1953, the White House had to undergo renovations during the Truman administration. Because they needed to relocate the President until the renovation was finished, the Secret Service requested information from the Census Bureau to help with background checks on residents living in a proposed relocation area.
Their request was denied because census data are confidential even to the President. Ultimately President Truman relocated at Blair House.
Yes, but how motivated are Census workers to protect my answers?
First, Census workers must pass security and employment reference checks. Secondly, all Census Bureau employees face a $250,000 FINE AND/OR PRISON TERM if they disclose information that can identify a census respondent or household.