The board of supervisors shall cause a notice embodying the order in substance, signed by the chairman and clerk of the board, to be issued and published, giving public notice of the organizational election, the time and polling places, and specifying the matters to be submitted to the vote of the electors of the proposed district. The notice and order shall be published once a week for at least three weeks prior to the election in a newspaper of general circulation in the county. If any portion of the proposed district lies within any other county or counties, the notice and order shall be published in a newspaper of general circulation published in each of such counties. A copy of the notice and order shall be posted in at least one conspicuous place in each of the divisions of the proposed district for at least two weeks prior to the date of the election.