Section 1. From and after the effective date of this Act, the salaries of county superintendents of public instruction in all counties in this State having a population of not less than twenty-three thousand, six hundred and twenty (23,620) nor more than twenty-three thousand, eight hundred (23,800), according to the last Federal Census, shall be in a sum not less than Twenty-two Hundred Dollars ($2200) and not more than Three Thousand Dollars ($3,000). The salaries of county superintendents of public instruction in all counties in this State having a population of not less than twelve thousand, four hundred and sixty (12,460) and not more than twelve thousand seven hundred and eighty (12,780), according to the last preceding Federal Census, shall be in a sum not less than Eighteen Hundred Dollars ($1800) and not more than Twenty-four Hundred Dollars ($2400).