The common council of any city, or the corporate authorities of any village, in this state, shall have the power to levy a special tax not to exceed in any 1 year 4 mills on the dollar of the assessed valuation of all taxable property within the said city or village, to be used for advertising, exploiting and making known the industrial, commercial, educational or recreational advantages of the said city or village, and to establish recreational and educational projects for the purpose of encouraging immigration to, and increasing the trade, business and industries of the said city or village: Provided, however, That such tax levy shall not exceed 50,000 dollars in any 1 year.