In 1974 the overwhelming majority of commercially published works in the US was public domain.
Before 1972 in the US, the public’s understanding of copyright was that it is a temporary advantage given to authors.
Congress: “US Congress’s protection of copyrights is not a “special private benefit,” but is meant to achieve an important public interest: “to motivate the creative activity of authors and inventors by the provision of a special reward, and to allow the public access to the products of their genius after the limited period of exclusive control has expired.”
US Congress: “The granting of such exclusive rights [copyrights] under the proper terms and conditions, cofers a benefit upon the public that outweighs the evils of the temporary monopoly.“
By the provision of a temporary monopoly, parliament (UK) or congress (US) hoped to encourage the progress of learning and bribe authors into generating materials for the public domain as to benefit all people. It is not designed to benefit authors.
Human beings have incredibly short memories. In 1974 the overwhelming majority of commercially published works in the US was public domain. In order to receive the privilege of copyright, you must show that you will be distributing copies, you must pay a fee, your copies must be marked with a copyright notice. Notice of copyright – the familiar C-in-a-circle, along with the name of the copyright holder, the date first published, when the copyright will expire, to whom you must address to request permission and contact details. Failing to provide an accurate notice will cause you to LOSE YOUR COPYRIGHT. It turns out the vast majority of publishers in the 70s didn’t care to register copyright. It was never really that useful. [Source:Jessica Litman – Sharing & Stealing] .