It looks like[0] as of the start of this year, only works made in 1927 or earlier are in the public domain. Copyright terms have regularly been extended by Congress and they are astoundingly long now.
Thanks to Disney, this aspect of our economy and culture is completely broken.
There has been no appetite for extending terms in recent years, and things are entering the public domain again, including _Steamboat Willie_. I think there is an understanding that the CTEA will end up as the final extension and that further extensions are unlikely.