I posted on the first winner, His Family, (on Dabbling Dilettante) back in June. Then I posted on the fifth in September which was One of Ours. Now I'm on the eighth, Arrowsmith by Sinclair Lewis. So, I've been a little bit sporadic.
Here's what I can tell you so far: Out of the first eight books, six of them take place in the midwest. Two in New York. Interesting, I think. And it looks like the ninth, Early Autumn by Louis Bromfield might, too. And almost all deal with the characters coming to grips with the social, geographic, economic, civic changes of the late 19th century. This is understandable. They went from horses to cars in a matter of a few years, city and town layouts changed, the way people lived and worked and where they lived changed, etc. But why such a focus on the midwest?
First of all, most of the authors are from that part of the country:
1918 His Family by Ernest Poole: from Chicago but this book takes place and is all about a changing turn-of-the-century New York
1919 The Magnificent Ambersons by Booth Tarkington: from Indianapolis; Indiana is important in much of his work--This book takes place in Indianapolis though not named
1920 (No Award)
1921 The Age of Innocence by Edith Wharton: New Yorker, born and bred
1922 Alice Adams by Booth Tarkington: takes place in midwest: see above
1923 One of Ours by Willa Cather: born in Virginia but moved with her family to Nebraska as a child; well-known for Nebraska works such as My Antonia--This book takes place in Nebraska
1924 The Able McLaughlins by Margaret Wilson born in Iowa--book takes place in Iowa
1925 So Big by Edna Ferber born in Michigan, lived in Wisconsin--book takes place in and around Chicago
1926 Arrowsmith by Sinclair Lewis born in Minnesota--book takes place in a fictional place called Zenith, Winnemac, near Illinois.
1927 Early Autumn by Louis Bromfield from Ohio, defined as a Midwestern-American writer--not sure where book takes place as I haven't gotten there yet, but I'm thinking midwest.
Just an observation so far. Reading chronologically gets you looking for patterns, I guess.