 Construction then moved to the western half of the state . A new 20 @-@ mile @-@ long ( 32 km ) section from US 71 west to US 59 north of Avoca opened in December 1965 . A year later , the interstate was 90 % completed when two stretches , a 50 @-@ mile @-@ long ( 80 km ) stretch from US 59 to I @-@ 29 , which included 16 miles ( 26 km ) of I @-@ 80N and the missing 25 @-@ mile @-@ long ( 40 km ) section between the western section and Des Moines , each opened to traffic . Sections of I @-@ 80 in the Council Bluffs area did not open for another couple years . A short section between Madison Avenue and US 6 opened in 1968 . The interstate was completed from the eastern junction with I @-@ 29 to I @-@ 80N in late December 1969 . 
