OK. This one is predictable. Its the Declaration of Independence, followed by the Constitution and the Bill of Rights as #3.
The People's Vote, co-sponsored by the National Archives and Records Administration, National History Day, and U.S. News & World Report, invited Americans of all ages and educational backgrounds to vote for 10 of 100 milestone documents drawn mainly from the holdings of the National Archives.
The rest of the Top 100 are interesting.