William Carlos Williams, Frank O'Hara, and the New York Art Scene Book

The first half of the book discusses the economic, social, and political climate of the late 19th century, focusing on the last decade, when the argument about whether silver or gold (or both) should be used to support or supplement the money supply in the United States. This it does very well. I just taught that unit a couple of months ago in my US History class, and I had completed a survey biography of McKinley right before the New Year, and many of the discussions and insights were aligned with what and how I taught the material in the classroom.
The second half of the book is Baum's classic, annotated with footnotes. This format was distracting to me, but I will admit it is probably a personal preference thing. I would much rather have had the annotations and notes embedded in the text of the short novel. It was a little "disturbing" in the flow of reading to search the footnotes, resulting in a very disjointed reading experience (once I realized it was breaking up my rhythm I approached it differently by just reading the entire chapter (they are all fairly short), going back to the relevant portion of the story to re-read it THEN checking out the footnotes. Your style of reading may and probably will be different than mine.
Having grown up knowing all I know about the Wizard of Oz just came from the movie. As any student of film knows, any movie based on a book has significant or maybe minor or trivial changes. Some of the changes between the book and the movie would not necessarily cause one to see some of the allegory in the way Baum may (?) have intended. Remember, the editor is interpreting Baum's work in this way; it doesn't mean that he is right in his analysis, it is simply "an" interpretation not "the" or "the only" or "the correct" interpretation. The editor does make some interesting insights, and some of his work is based on the analysis and interpretations of various other economists and political historians.
At any rate, I can recommend this "Historian's Oz" for any student or lay person interested in US History that is especially interested in the economic forces behind history's journey (those of you that know me know that I see historical events as results of economic forces). So I enjoyed this book more than, say, the "average" reader would have. BUT, if you want a "jumping-off point" to dive into late 19th century economic history, this is a good place to start.