Today copyright protection is in fact much longer than 75 years in the US.
For personal works, it's life of author + 70 years. So if you write a poem today and live another 60 years, your poem will enter public domain in the year 2145.
For "works made for hire" (which includes most commercial works), the term of copyright is either 95 years from publication or 120 years from creation, whichever is shorter.
So the movie "Ant Man" will enter public domain in 2110... Assuming that the US Congress doesn't extend the deadline indefinitely (which the Supreme Court has permitted).
For personal works, it's life of author + 70 years. So if you write a poem today and live another 60 years, your poem will enter public domain in the year 2145.
For "works made for hire" (which includes most commercial works), the term of copyright is either 95 years from publication or 120 years from creation, whichever is shorter.
So the movie "Ant Man" will enter public domain in 2110... Assuming that the US Congress doesn't extend the deadline indefinitely (which the Supreme Court has permitted).
Law text: https://www.law.cornell.edu/uscode/text/17/302