What was the "Biggest Indian Contest?"

This morning I received an email from Seattle-area historian Knute Berger with this wonderful image attached. The picture is from the Spokane Historic Preservation Office image collection at the Washington State Archives, Digital Archives where I work. The caption reads: "Spokane Mayor Burch with 'Biggest Indian' Contest Winner" and lists the photographer as Charles Libby.

Knute wondered if I knew anything more about this striking and a little strange image. I do not. I know that Arthur W. Burch was mayor of Spokane from 1935 until 1937, so that dates the photograph. A Goggle search suggests that "biggest Indian" contests were something of a thing in the early-20th century and are continued by a few First Nations groups in Canada today. And that is all I have.

But why should I do all the work on this blog? Dear readers, does anyone know anything more about this contest or this photograph? What was the "Biggest Indian Contest?" Where was the photograph taken? Who is the winner? How long did the contest continue?

I'd love to know more about this image.