Duke University’s Center for the Study of the Public Domain:
Current US law extends copyright for 70 years after the date of the author’s death, and corporate “works-for-hire” are copyrighted for 95 years after publication. But prior to the 1976 Copyright Act (which became effective in 1978), the maximum copyright term was 56 years—an initial term of 28 years, renewable for another 28 years. Under those laws, works published in 1961 would enter the public domain on January 1, 2018, where they would be “free as the air to common use.” Under current copyright law, we’ll have to wait until 2057. And no published works will enter our public domain until 2019. The laws in other countries are different—thousands of works are entering the public domain in Canada and the EU on January 1.
The good news is that this is, theoretically, the last year since 1998 where no new works will enter the public domain in the United States. The bad news is that you can bet that Disney will — as ever — lobby hard to extend that public domain drought for several more years.