A steam locomotive crosses the magnificent stone-arch Great Northern Viaduct as the Mississippi River churns below at St. Anthony Falls — the only natural waterfall on the entire Mississippi — while the flour mill skyline of Minneapolis looms in industrial grandeur behind, and two solitary figures lean on a railing in the foreground watching it all unfold around 1907. This undivided-back-era card captures Minneapolis at its industrial zenith, when the city milled more flour than anywhere on earth and the railroads were the arteries of a continent.