Do you have to be an American citizen to be able to register works with the Copyright Office?
No. Foreign authors may register their works with the U.S. Copyright Office in order to obtain the statutory benefits of registration in the United States. Foreign authors should pay attention to the deposit requirements. If the work was first published in the United States, the applicant may need to submit two copies of the best edition of the work, along with the application and fee. If the work was first published outside of the United States, only one copy is required for deposit. To register an unpublished foreign work, the applicant need only submit one complete copy of the work containing all of the authorship claimed on the application. For more information on the deposit requirements for foreign works, please see Compendium (Third) § 1503.