The duration of a copyright protection depends on several factors, like the date the work was created, published, or registered, or like whether it was created by an individual or an employee.
In general, the following time periods are the most important if you want to determine whether a work is still under copyright protection or not.
From 1978 to date
According to the Copyright Act of 1976, which changed many things in Copyright Law until today, for works created by an individual after January 1, 1978, copyright protection lasts for the life of the creator plus 70 years. For an anonymous or a pseudonymous work, or a work made for hire, the copyright lasts for 95 years from the year of its first publication, or 120 years from the year of its creation, whichever is shorter.
For all these works no renewal registration is needed.
For works before January 1, 1978, things are more complicated, with the duration also depending on whether the copyright was renewed.
From 1964 to 1978
Copyright protection lasts for 28 years from the date of publication, with an automatic renewal of an additional 67 years.
From 1922 to 1963
Copyright protection lasts for 28 years from the date of their publication. If the copyright was renewed during the 28th year, the copyright was extended for an additional 67-year period.
From 1909 to 1921
Copyright protection lasts for 28 years from the date of publication. If the copyright was renewed during the 28th year, the copyright was extended for an additional 28-year period.
After copyright expires, a work becomes part of the public domain and then may be freely copied or distributed.