Top billing was NOT Ida Lupino, it was Glenn Ford.
I continually see this movie described with Ida Lupino getting top billing over Glen Ford. If you look at the poster for the movie, this was clearly not the situation when the movie came out in 1949. And after all, the main character in the movie WAS Glenn Ford's character, Jacob 'Dutch' Walz. He was the person after whom the famous mine was named. Heck, the main image used has even been changed for the distribution of the DVD and yet LOOK, right at the top of the DVD cover over the image it says, "GLENN FORD", not "IDA LUPINO".
Ida Lupino was a great actress and directer in her own right, but giving her top billing in this movie after the fact is just WRONG! IMO, this is just a small indication of the fact that the power which women have over America is totally out of control. As the ancient Egyptians would say, "The balance of Thoth and Maat is disturbed."