For the next , I-80 runs in more or less a straight line. Interchanges occur at regular intervals; of Pottwattamie and Cass county farmland separate each exit from the next. Near Avoca, it crosses the West Nishnabotna River and meets US 59. East of the interchange, the Interstate crosses the eastern branch of the West Nishnabotna. As I-80 approaches the area north of Atlantic, there are three interchanges, Iowa 173, County Road N16 (CR N16), and US 71, which serve the western, central, and eastern parts of the city, respectively. Iowa 173, which serves Atlantic by way of Iowa 83, also connects to Elk Horn and Kimballton. US 71, which continues north towards Carroll, carries US 6 traffic to the Interstate. At this point, US 6 begins the first of three instances when its traffic is routed along I-80. In the eastern part of Cass County, the two routes meet the northern end of Iowa 148.