Sec. 489(60). Other than official signs prohibited.
No unauthorized person shall erect or maintain upon any highway
any warning or direction sign, marker, signal or light in imitation
of any official sign, marker, signal or light erected under
the provisions of this section, and no person shall erect or maintain
upon any highway any traffic or highway sign or signal bearing
thereon any commercial advertising, provided nothing in this
subsection shall be construed to prohibit the erection or maintenance
of signs, markers, or signals thereon the name of an organization
authorized to erect the same by the State Highway
Commission, Mayor or City Manager.