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. As I-80 and US 6 approach Adair, the highways curve slightly to the south to bypass the community. There are two interchanges in Adair; both of the intersecting roads, at one time or another, carried US 6. CR G30, the White Pole Road, was the original alignment of US 6, while CR N54 has not carried US 6 since 1980. Further east is an interchange with Iowa 25. About south of the interchange is Freedom Rock. Each year for Memorial Day, the rock is repainted with a patriotic scene by local artist Ray "Bubba" Sorenson II. Near Dexter, I-80 and US 6 graze the northwestern corner of Madison County. After , the routes enter Dallas County and meet CR F60, another former alignment of US 6. Central Iowa Continuing east, the two routes follow a due-east section of highway, where they pass Earlham. Near the CR F90/CR P58 interchange, they start heading northeast towards Des Moines. At De Soto, US 6 splits away from I-80 at the interchange with US 169. Tourists who want to see the covered bridges of Madison County (made famous by the book The Bridges of Madison County) and the birthplace of John Wayne, are directed to follow US 169 south to Winterset. Between De Soto and Van Meter, the Interstate crosses the middle and north branches of the Raccoon River, which converge just south of the crossing of the North Raccoon River. As the highway gets closer to Des Moines, it moves more sharply to the northeast. In southern Waukee, there is an interchange with Grand Prairie Parkway, the first diverging diamond interchange in the state. As I-80 enters West Des Moines, the speed limit lowers to and the path of the Interstate straightens out to the east at the Jordan Creek Parkway exit. The highway adds a third lane eastbound and drops the third lane westbound. Almost to the east is the interchange with I-35, which also marks the beginning of I-235. Eastbound I-80 exits the freeway via a flyover ramp to northbound I-35; eastbound I-235 begins as the continuation of the I-80 freeway. Locally, this exit is called the West Mixmaster. I-80 shares the next with I-35 on a six-lane freeway where each direction's three