It are six bridges along current or former sections of US 2 that MDOT has added to its listing of Michigan 's Historic Bridges ; two of these are also listed on the National Register of Historic Places ( NRHP ) . A third bridge added to the NRHP in late 2012 has not been added to MDOT 's listing however . The first of these historic bridges is the crossing of the Iron River , which has since been bypassed by a new bridge . The original structure , dating to 1918 , is a 55 @-@ foot @-@ long ( 17 m ) spandrel arch span that was built by the MSHD as Trunk Line Bridge No. 191 . The structure was listed on the NRHP on December 9 , 1999 , for its architectural and engineering significance .