Prior to the mass media and instant entertainment we have today there was live entertainment. There were various lectures, dramatic readings, and, of course, plays. Shakespeare was naturally a cultural cornerstone to stage productions and his comedies and dramas were still very much a staple over 250 years later.
Anderegg has produced an excellent study as to how Americans in Lincoln's time would have known Shakespeare's works, either in print or as produced on the stage at the time. That Lincoln himself was familiar with Shakespeare's works is well-known; although he did not quote Shakespeare hardly at all in his speeches or writings Lincoln did write about Shakespeare and expressed an opinion of productions and even read passages aloud amongst his friends and associates. Anderegg has meticulously researched Lincoln's movements and whether Lincoln might have been able to attend that performance or another.
This is a fine book on the topic and Anderegg's research makes the reader feel as if he or she really has a firm understanding of Lincoln's love of Shakespeare and why it was so important to him.