 In eastern Iowa , new sections of road were opened in series . 1962 saw the eastern section extended 20 miles west to Iowa City and the central section was extended 25 miles east to Grinnell . Iowa City 's section of interstate was completed on November 15 , 1963 . A 60 @-@ mile @-@ long ( 97 km ) section , the longest section to be opened at one time , connected the two sections in October 1964 . The easternmost section of I @-@ 80 , from US 61 to US 67 at the Mississippi River , opened a month later . This gave travelers nearly 185 miles ( 298 km ) of uninterrupted freeway driving . 
