An ad valorem tax of two mills on each dollar of the total assessed valuation of all the taxable property in each county or counties in the State of Mississippi in which there is located a city or town upon any river or waters, which rivers or waters separate two United States highways, which highways are separated by such water but are otherwise connected by the streets of a municipality in said county connecting said highways except for said water, is hereby levied on all said taxable property in said county in or for each year in which the principal of or interest on any bonds or other obligations issued by any municipality or county pursuant to this chapter becomes due. The receipts from said two-mill tax shall be withheld by the tax collector of said county, or by any other tax collecting agency authorized by law for the collection of said taxes, from receipts from state ad valorem taxes now in effect or which may be hereafter levied, so long as said state ad valorem shall be not less than the said two-mill tax herein levied. If no state ad valorem taxes equal to or greater than the said two-mill tax herein levied is levied, then, and in that event, the said two-mill tax herein levied shall continue to be levied and collected as herein provided in each such county or counties in or for each year in which the principal of or interest on any bonds or other obligations issued by any municipality pursuant to this chapter becomes due.