CM and StP Railroad Underpass is a historic structure located southwest of Washington, Iowa, United States. It was listed on the National Register of Historic Places in 1998. The Warren deck truss bridge is a rare example of this type of bridge in Iowa, and the oldest still in existence.[2] Given the relatively flat nature of Iowa's rivers and streams this bridge type was rarely built in the state, and was mostly built for railroad use.[2] This bridge, completed in 1903 by the Chicago, Milwaukee, St. Paul & Pacific Railroad (known as simply The Milwaukee Road), crosses a county highway bridge and the west fork of Crooked Creek.
