(a) There are hereby established eight classes of municipalities based on the population as certified by the 1970 federal decennial census, as authorized by Amendment No. 375, Constitution of Alabama of 1901, as follows:
Class 1: All cities with a population of 300,000 inhabitants or more;
Class 2: All cities with a population of not less than 175,000 and not more than 299,999 inhabitants;
Class 3: All cities with a population of not less than 100,000 and not more than 174,999 inhabitants;
Class 4: All cities with a population of not less than 50,000 and not more than 99,999 inhabitants;
Class 5: All cities with a population of not less than 25,000 and not more than 49,999 inhabitants;
Class 6: All cities with a population of not less than 12,000 and not more than 24,999 inhabitants;
Class 7: All cities with a population of not less than 6,000 and not more than 11,999 inhabitants;
Class 8: All cities and towns with a population of 5,999 inhabitants or less.
(b) The Legislature may refer, in the title thereof, to the class or classes of municipalities herein set out, in adopting general laws.
(c) Any municipality incorporated after June 28, 1979, shall be placed in one of the above classes according to the population of the municipality at the time of its incorporation.