The Whistler radio show was sponsored by The Signal Oil Co. - and going by their advertisements in the show, were pretty much limited to the West Coast. The show was often mentioned as the most popular West Coast show on radio. Would there have been much interest in this movie (and its sequels) in the rest of the nation?
shareThe fact that it was based on such a successful radio series probably did interest audiences throughout the rest of the country somewhat. Those people who loved a good mystery movie would have been naturally interested in it, as well as fans of Richard Dix, who had been a big star in the silent movie era. It must have been a big draw because more in the series were made.
"All necessary truth is its own evidence." - Ralph Waldo Emerson