Copyright has crept. It is increased in both length and coverage for 170 years. If I am interpreting Siva Vaidhyanatha in Copyrights and Copywrongs correctly, the following chart should summarize their progression:
NB: Copyright law is complex. What is shown above is a very rough summary–the extension that came into effect in 1978 was passed in 1976 and was for the life of the author plus 50 years. The 1998 extension was for the life of the author plus 90 years for works copyrighted after 1998 and plus 70 years for works copyrighted before. For this chart, I am positing the extreme scenario where a finger-paint drawing made by a 2-year old is still under copyright when they die at 98, and will go on for 90 more years. In this scenario, the life of the copyright is de facto 190 years.
Imagine is the 1909 act was never passed. Copyright would be for a total maximum of 42 years (28 years then 14 more as an extension). That is where the next post will pick up.