due to getting tied up with legal deposit in Australia i just looked at the situation on a wider basis and found this:
In Canada, the Library and Archives of Canada Act (2004) specifies that up to two copies of any published material must be deposited with Library and Archives Canada. Materials deposited in the archives are catalogued; the catalogs are available as part of the Library and Archives Canada website. The province of Quebec also requires deposit of two copies of any document be deposited to Bibliothèque et Archives nationales du Québec within 7 days of its publication.
In the United States, any copyrighted and published work must be submitted in two copies to the United States Copyright Office at the Library of Congress. This mandatory deposit is not required to possess copyright of unpublished works, but a copyright registration can give an author enhanced remedies in case of a copyright violation. The Library of Congress does not retain all works.