The organic act passed by the U.S. Congress which established Juneau as the capital also allowed Alaskan communities to incorporate for the first time.
Following the passage of the organic act, Juneau's incorporation petition was certified and the first election of officials occurred on June 29, 1900.
Douglas, located a short distance southwest of Juneau across Gastineau Channel, followed suit by incorporating on March 29, 1902.
The Greater Juneau Borough was incorporated in October 1963, established by an act of the state legislature earlier that year (Chapter 52, Session Laws of Alaska 1963) which required the most populous election districts in the state to incorporate as boroughs by January 1, 1964.
Several years after that, Juneau, Douglas and the borough unified to form the current municipality, which incorporated on July 1, 1970.