Whenever a united city is formed by a compliance with Section 7-2-1 and the decision is in favor of an alderperson form of municipal government, the united city shall be governed, after the first election held in compliance with Section 7-2-7, by a council composed of a mayor and a board of alderpersons selected by the electors of the united city as provided by the provisions of this Code relating to the election of city officers, except that all elections in a united city are controlled by the City Election Law as provided in Section 7-2-6.