At the time fixed in the notice or on any adjourned day thereafter, any person interested may appear and be heard at a public hearing before the county board of the county in which the petition is filed. After such hearing, if the county board shall find from the evidence produced that (1) such tract is suitable for use as an industrial area, (2) it will be generally beneficial to the community, and (3) the owners of all the land embraced therein have consented to such designation, such board shall designate such tract as an industrial area and cause a certified copy of such order to be filed and recorded in the offices of the county assessor and the register of deeds of the county or counties in which the real estate is situated. If such tract is located in whole or in part within an unincorporated area over which any city or village exercises zoning control, the designation of such tract as an industrial area must first be approved by the municipal legislative body.