 Before I @-@ 80 was planned , the route between Council Bluffs and Davenport , which passed through Des Moines , was vital to the state . Two competing auto trails , the Great White Way and the River @-@ to @-@ River Road , sought to be the best path to connect three of the state 's major population centers . The two trails combined in the 1920s and eventually became U.S. Highway 32 ( US 32 ) in 1926 . US 6 , which had taken the place of US 32 , became the busiest highway in the state . In the early 1950s , plans were drawn up to build an Iowa Turnpike , to be the first modern four @-@ lane highway in the state , along the US 6 corridor . Plans for the turnpike were shelved when the Interstate Highway System was created in 1956 . 
