Any county, municipality or other political subdivision of this State, by resolution or ordinance duly passed and approved, may exempt from taxation and assessment for public purposes for a period up to 20 years, any structure above or under the ground which may hereafter be constructed and located within the county, municipality or other political subdivisions of this State and used by the public for the parking of automobiles off the street or highway. The exemption shall be limited to that portion of the structure exclusively used for or devoted to the parking of automobiles and vehicles of that nature.