Mo. Rev. Stat. § 300.465: Parking prohibited on narrow streets.

1. The city traffic engineer is authorized to erect signs indicating no parking upon any street when the width of the roadway does not exceed twenty feet, or upon one side of a street as indicated by such signs when the width of the roadway does not exceed thirty feet.

2. When official signs prohibiting parking are erected upon narrow streets as authorized herein, no person shall park a vehicle upon any such street in violation of any such sign.