The box hangs on a wall at the 9/11 memorial preview site. Memorial officials believe the money was slipped into the box sometime between 5 p.m. -- when the box was last checked -- and 7 p.m., when the preview site closed.
Officials believe the donation was made by a single person. They say the bills appeared to have been recently withdrawn from the bank.
Daniels said officials would love to know the donor's name so they could say thank you.