Mo. Rev. Stat. § 91.140

In case a proposition is made by the person, firm or corporation owning the plant in the city for the sale thereof under sections 91.090 to 91.300, and in case the city council fails or neglects to submit said proposition as herein provided, then upon the filing with the city clerk of said city a petition signed by one hundred taxpaying citizens of the city, requesting the submission of such proposition, as above provided, it shall be the duty of the city council and the mayor of such city to duly enact an ordinance submitting the said proposition to the voters of said city, as herein provided.