Gustavus is a second-class city in Hoonah-Angoon Census Area in the U.S. state of Alaska. According to the 2020 census, its population of …Gustavus is a second-class city in Hoonah-Angoon Census Area in the U.S. state of Alaska. According to the 2020 census, its population of 655, reflects a 48% increase from 442 in the 2010 census, making it one of the fastest growing communities in Alaska.