It shall be unlawful to drive any motor vehicle on any street not under the jurisdiction of the department of transportation of the state and for which the county or the county highway commissioner does not have maintenance responsibility, in an urban district within the village at a speed in excess of twenty (20) miles per hour, or in an alley at a speed in excess of fifteen (15) miles per hour, as indicated by appropriate signs erected at the proper place giving notice of such limit. "Urban district" is defined to be the territory contiguous to and including any street which is built up with structures devoted to business, industry, or dwelling houses situated at intervals of less than one hundred feet (100') for a distance of a quarter of a mile or more. (Ord. 4-2002, 1-8-2002)