(1) Each county shall be classified according to the county's population.
(2)
(a) A county with a population of 1,150,000 or more is a county of the first class.
(b) A county with a population of 260,000 or more but less than 1,150,000 is a county of the second class.
(c) A county with a population of 40,000 or more but less than 260,000 is a county of the third class.
(d) A county with a population of 12,000 or more but less than 40,000 is a county of the fourth class.
(e) A county with a population of 5,000 or more but less than 12,000 is a county of the fifth class.
(f) A county with a population less than 5,000 is a county of the sixth class.