Pulaski County Bridge No. 31 is a Stearns truss bridge originally built in 1905 in Pulaski County in the U.S. state of Indiana. In 2006, it was disassembled at its location over Big Monon Ditch, near Medaryville in Pulaski County, and moved to the Wabash and Erie Canal park in Delphi in Carroll County, Indiana. It was added to the National Register of Historic Places (NRHP) in 2003, thanks to the efforts of a local Boy Scout. It is believed to be the last surviving Stearns Truss Bridge in the United States.