|Found: Grand Ave. Viaduct, Milwaukee, Wis. by E. C. Kropp Co., Milwaukee, circa 1920s|
|Found: Second Street Bridge, Burlington, Wis. by E.C. Kropp Co., Milwaukee circa 1920s|
|Found: Davenport Street Bridge, Wisconsin River, Rhinelander, Wis. Substantial industries give Rhinelander a firm economic foundation. Paper and lumber products, refrigerators and many other manufactured produccts find their way into the great trade channels of the world" by E.C. Kropp Co., Milwaukee, Wis. postmarked October 1, 1948|
E.C. Kropp was apparently fascinated with the wonders of modern engineering.