Before 1978, works that were not "published" according to federal copyright law were subject to state law until they were published, at which point, if they had a copyright notice, they would be subject to federal copyright law. Works "published" before 1964 had to be renewed 28 years after the date of first publication, or they would enter the public domain.
However, although it is not clear under the 1909 Act, courts have ruled that merely broadcasting a work to the public does not constitute "publication."
Nevertheless, the 1909 Act also allowed unpublished works to be registered with the Copyright Office to obtain federal copyright protection. In such a case, the date of registration of such a work is considered to be the date of first publication for the purposes of determining both the length of the copyright term and the year when the copyright had to be renewed (if at all). Therefore, if an unpublished work was registered with the Copyright Office prior to 1964 and was not subsequently renewed, it is now in the public domain.