Iowa Code Title VIII. Transportation [Chs. 306-330B] § 321.289. Speed signs--duty to install

The department shall furnish and place on primary roads or on extensions of primary roads within any city suitable standard signs showing the points at which the rate of speed changes and the maximum rate of speed in the district which the vehicle is entering. On all other main highways the city shall furnish and erect suitable signs giving similar information to traffic on such highways.