 Over the next 45 miles ( 72 km ) , US 30 passes through a small town every four to seven miles ( 6 to 11 km ) . In Cedar County it passes through Mechanicsville , Stanwood , Clarence and Lowden . In Stanwood , it is overlapped by Iowa 38 for one mile ( 1 @.@ 6 km ) . In Clinton County , it passes through Wheatland , Calamus , and Grand Mound before reaching a full cloverleaf interchange with US 61 at DeWitt . US 30 overlaps US 61 for one mile ( 1 @.@ 6 km ) , crossing the Union Pacific Overland Route in the process , and leaves US 61 via a trumpet interchange . 
