There are 26 counties in Alaska. The most populous county in the U.S. state of Alaska is Anchorage Municipality. With a population of 291,538 in 2019, Anchorage Municipality has seen a growth rate of -0.60% since the time of the 2010 census. Following Anchorage Municipality, the next three most populous counties are Matanuska-Susitna Borough (107,610), Fairbanks North Star Borough (98,971), and Kenai Peninsula Borough (58,533). These are the only boroughs with populations of more than 40,000 in Alaska. Only Anchorage Municipality experienced a population decline. The greatest increase in population happened in Matanuska-Susitna Borough which grew 19.92% since 2010.
The least populous county in Alaska is Yakutat City and Borough with a population of only 604 following a growth decrease of 8.76% since the 2010 U.S. census. Other small counties behind Yakutat City and Borough are Bristol Bay Borough (877), Skagway Municipality (1,148), and Lake and Peninsula Borough (1,587). All of these counties experienced a negative population growth of up to -12.48% (Bristol Bay Borough) except Skagway Municipality which grew 18.60%.
The county with the most rapid rate of growth in Alaska is Matanuska-Susitna Borough. Matanuska-Susitna Borough has seen a growth rate of 19.92% since the 2010 U.S. census, and as of 2019 has a population of 107,610. Behind Matanuska-Sustina Borough in terms of population growth is Skagway Municipality (18.86%), Denali Borough (12.21%), and Kusilvak Census Area (11.23%). These are the only counties with double-digit growth. Bristol Bay Borough has seen the largest decrease in population with a growth rate of -12.48%.