A Hospital District may be created, incorporated and managed as provided in this Act and may exercise the powers herein granted or necessarily implied. A Hospital District may include municipalities or territory not in municipalities or both or territory in one or more counties; provided, that the provisions of this Act shall not be effective in counties having a population of more than 1,000,000 inhabitants. The territory of any municipality shall not be divided and the territory contained within the corporate limits of an existing Hospital District shall not be incorporated in another Hospital District.