 As it enters Cedar County , it passes West Branch , the birthplace of and site of the library and museum of President Herbert Hoover . It approaches the Cedar River near the village of Rochester . Just east of the river crossing , Iowa 38 joins I @-@ 80 from the north . The county road that continues to the south from Iowa 38 leads to Moscow . The two highways travel together for four miles ( 6 @.@ 4 km ) until they reach the Wilton area . Here , Iowa 38 exits to the south , while US 6 joins I @-@ 80 for the last time . 
