 In Iowa , Interstate 680 is markedly less urban than in Nebraska . The first three miles ( 4 @.@ 8 km ) of I @-@ 680 travel through the flat bottoms of the Missouri River valley . At the interchange west of Crescent , eastbound I @-@ 680 joins northbound I @-@ 29 for just under ten miles ( 16 km ) . The north – south stretch of I @-@ 29 / I @-@ 680 sits approximately halfway between the Missouri River and the Loess Hills . Near the unincorporated village of Loveland , I @-@ 680 exits from I @-@ 29 and turns east again , immediately entering the Loess Hills . 
