Your best bet would be local newspapers. Don’t just check the ads for the theater, because the music may be mentioned in reviews of films that are showing. Most musicians were anonymous though, except in big theaters in big cities.
Jim is correct that trade magazines like Moving Picture World have a lot of business and exhibitor information in them. And it is also arranged by region of the country. You would have to look at microfilm copies of this magazine, or find a collector who has some copies.
Your best bet would be local newspapers. Don’t just check the ads for the theater, because the music may be mentioned in reviews of films that are showing. Most musicians were anonymous though, except in big theaters in big cities.
Jim is correct that trade magazines like Moving Picture World have a lot of business and exhibitor information in them. And it is also arranged by region of the country. You would have to look at microfilm copies of this magazine, or find a collector who has some copies.