I am in the middle of my search, but so far have found a bunch of material from two newspapers I have not looked at before, the Syracuse Herald (from Syracuse, New York) and the Davenport Democrat and Leader (from Davenport, Iowa). I scored film reviews, articles and advertisements. I was especially happy to get at these two papers, as Syracuse and Davenport each hosted the Denishawn Dance company during the time Louise Brooks was with the group. Resultingly, I found a few more articles. Here is a nifty little piece I uncovered from the Syracuse Herald from March, 1926.
NewspaperArchive.com has also added the Oakland Tribune (from Oakland, California) to its holdings. Though I have previously gone through this newspaper on microfilm at the Oakland Public Library, I took the opportunity to search this database by keyword. And I came up with a handful of new items, including a few film reviews dating from the 1920's which I had missed before. One particular item which caught my attention was the mention of a 1974 screening of Prix de Beaute in San Francisco put on by Kenneth Anger. (The famed author, actor, and filmmaker used to live in San Francisco, and had known Brooks in Paris in the 1950's.) This screening was certainly one of the earliest in America - as the film was reportedly not shown in the United States in the 1930's. When I next visit the San Francisco Public Library, I will search the San Francisco papers for anything additional about this event.