Over the course of my lifetime, copyright law in the United States has undergone a complex evolution. Overall, this has meant that works effectively stopped entering the public domain. In 1979, everything published in the United States in 1921 or earlier was in the public domain. As 31 December 2018, the public domain had grown by exactly one year.
Large corporations, most notably Disney, fought for the last copyright extension back in 1998. Over the past few years, there have been some fears that they'd try for another extension. They didn't. As of today, therefore, anything published in the United States in 1923 is now in the public domain. From now on, each January 1st, another year of material will be available.
More details on what's been going on and what will happen next are available here.
Naturally, since the Deseret Alphabet Classics series has the public domain as its life-blood, this makes a difference to me. As of yesterday, Sir Arthur Conan Doyle's The Case for Spirit Photography was beyond the pale and unavailable for transliteration without express permission. Today it's not. (I know we have all been anxious to read it in the Deseret Alphabet.)
In practice, I don't know that I'll attempt anything published in 1923 over the course of the coming year. Ultimately that's not the point. The purpose of copyright law, as stated in the US Constitution, is "to promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries" (Article I, Section 8). There has been wide-spread feeling that indefinitely long copyrights stifles creativity, rather than encouraging it. Creativity has made one small step forward today. It's "Happy Birthday" all over again.