Unless otherwise specifically provided, the provisions of this article apply in each county described as follows:
(a) A county with a population of 70,000 or less, as determined by the 1940 federal census, and having two or more superior court judges.
(b) A county with a population of 280,000 and under 285,000.
(c) A county with a population of over 295,000 and under 500,000.
(d) A county with a population of 500,000 and under 700,000.
(e) A county with a population of 700,000 or over.