10,653,930,363,287.91$

http://www.treasurydirect.gov/NP/BPDLogin?application=np

Хорошая ссылочка. Можно посмотреть госдолг США. В том числе межправительственные займы*.

*Intragovernmental Holdings are Government Account Series securities held by Government trust funds, revolving funds, and special funds; and Federal Financing Bank securities. A small amount of marketable securities are held by government accounts.