Upon the completion of the annexation of any territory in accordance with law to any city included, or partially included, in a special transit service district, the city clerk shall file with the secretary of the district a certified copy of the ordinance, resolution or other document completing said annexation, containing a description of the territory so annexed. Unless the district within 90 days after such filing shall file with the city clerk the district’s written objections to the annexation to the special transit service district of said territory or portion thereof, such territory, or portion thereof, shall, upon the termination of such period be deemed
incorporated into and annexed to the special transit service district, and thereafter is subject to taxation, along with the entire territory of the special transit service district in accordance with the assessable valuation of the property thereof, for special transit service district purposes, and for the payment of any indebtedness theretofore or thereafter incurred by the special transit service district.