beat me to it
they are also microfilmed and given to the National Archives..
Since 1978, the State Department has been microfilming passport applications. Even when they are on microfilm, original papers are kept for 20 years. The microfilm is kept for 100 years. In addition, the department keeps forever any record of a birth or death of an American overseas.
I know & it got me to thinking...genealogy. there is a reason records are kept. We are a nation of immigrants and tracking family ancestry is a HUGE deal. The census dept also uses these records, thus even a more pertinent reason NOT to destroy records.