Petersburg (Tlingit: Gantiyaakw Séedi “Steamboat Channel”) is a census-designated place (CDP) in Petersburg Borough, Alaska, United States. The population was 2,948 at the 2010 census, down from 3,224 in 2000.
Petersburg is located on the north end of Mitkof Island, where the Wrangell Narrows meets Frederick Sound. Petersburg is halfway between Juneau, 190 km (120 mi) to the north, and Ketchikan, 180 km (110 mi) to the south.
According to the United States Census Bureau, the city has a total area of 46.0 square miles (119 km), of which, 43.9 square miles (114 km) of it is land and 2.2 square miles (5.7 km) of it (4.74%) is water.
Mitkof Island is largely covered by low mountains. The lowlands are mainly made up of muskeg, a type of soil made up of plants in various states of decomposition. It is approximately 20 miles from its north end to its south. The western side of the island borders the Wrangell Narrows, one of the six listed in Southeast Alaska. The Narrows provides a somewhat protected waterway for boats, and opens on the south end of the island into Sumner Straits. Mitkof Island has many creeks that empty into the Narrows, including Blind Slough, Falls Creek, Twin Creeks, and Spirit Creek.
According to the National Marine Fisheries Service, the town is the 15th-most lucrative fisheries port in the United States by volume. In 2011, 101 million pounds of fish and shellfish passed through Petersburg, with a dockside value of $65 million. That year Petersburg ranked as 13th in the nation in terms of the value of its catches.
Petersburg first appeared on the 1910 U.S. Census and incorporated that same year. In 2013, upon the creation of the Borough of Petersburg, it became a census-designated place (CDP).
As of the census of 2000, there were 3,224 people, 1,240 households, and 849 families residing in the city. The population density was 73.5 people per square mile (28.4/km²). There were 1,367 housing units at an average density of 31.2 per square mile (12.0/km²). The racial makeup of the city was 81.64% White, 0.31% Black or African American, 7.20% Native American or Alaska Native, 2.76% Asian, 0.19% Pacific Islander, 1.86% from other races, and 6.05% from two or more races. Hispanic or Latino of any race were 2.85% of the population.
There were 1,240 households out of which 38.4% had children under the age of 18 living with them, 54.2% were married couples living together, 9.3% had a female householder with no husband present, and 31.5% were non-families. 25.5% of all households were made up of individuals and 6.6% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.11.
In the city the population was spread out with 29.8% under the age of 18, 6.2% from 18 to 24, 30.6% from 25 to 44, 24.6% from 45 to 64, and 8.8% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 108.7 males. For every 100 females age 18 and over, there were 108.0 males.
The median income for a household in the city was $49,028, and the median income for a family was $54,934. Males had a median income of $42,135 versus $28,792 for females. The per capita income for the city was $25,827. About 3.3% of families and 5.0% of the population were below the poverty line, including 3.5% of those under age 18 and 4.2% of those age 65 or over.