Iowa Code § 321.347: Certain traffic control in cities subject to departmental approval.

Notwithstanding section 321.345, at intersections of through highways with boulevards or heavy traffic streets in cities, the city council, subject to the approval of the department, may determine that the through highway traffic shall come to a stop, may erect traffic-control signals, or may adopt such other means of handling the traffic as may be deemed practical and proper.