Anoka County (/əˈnoʊkə/ ə-NOH-kə) is the fourth-most-populous county in the U.S. state of Minnesota. As of the 2010 United States census, the population was 339,534. The county seat and namesake of the county is the City of Anoka, which is derived from the Dakota word anokatanhan meaning “on (or from) both sides,” referring to its location on the banks of the Rum River. The largest city in the county is the City of Blaine, the thirteenth-largest city in Minnesota and the eighth-largest Twin Cities suburb.
The Mississippi River flows southeasterly along the county’s southwestern boundary. The Rum River flows southerly through the western part of the county, discharging into the Mississippi at the county’s southwestern boundary. The terrain consists of low rolling wooded hills. The terrain slopes to the south and east; its highest point is a small hillock 1.2 mile (1.9 km) east of the county’s northwest corner, at 1,100′ (335m) ASL. Otherwise the terrain’s highest point is along the western part of the north boundary line, at 1,083′ (330m) ASL. The county has a total area of 446 square miles (1,160 km), of which 423 square miles (1,100 km) is land and 23 square miles (60 km) (5.2%) is water.
The 2000 United States Census listed 298,084 people, 106,428 households, and 79,395 families in the county. The population density was 705 sq mi (272/km²). There were 108,091 housing units at an average density of 256/sqmi (98.7/km²). The 2010 United States Census found that 330,844 people were in the county.
At the time of the 2000 Census, the racial makeup of the county was 93.64 percent white, 1.60 percent black or African American, 0.70 percent Native American, 1.69 percent Asian, 0.02 percent Pacific Islander, 0.65 percent from other races, and 1.71 percent from two or more races, and 1.66 percent of the population were Hispanic or Latino of any race. The 2000 Census found 30.2 percent were of German, 14.3 percent Norwegian, 9.0 percent Swedish, 7.3 percent Irish and 5.9 percent Polish ancestry.
There were 106,428 households out of which 39.90% had children under the age of 18 living with them, 60.70% were married couples living together, 9.80% had a female householder with no husband present, and 25.40% were non-families. Of all households, 19.30% were made up of individuals and 5.30% had someone living alone who was 65 years of age or older. The average household size was 2.77 and the average family size was 3.19.
The county population contained 28.90% under the age of 18, 8.30% from 18 to 24, 34.10% from 25 to 44, 21.60% from 45 to 64, and 7.10% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 101.10 males. For every 100 females age 18 and over, there were 99.30 males.
The median income for a household in the county was $57,754, and the median income for a family was $64,261. Males had a median income of $41,527 versus $30,534 for females. The per capita income for the county was $23,297. About 2.90% of families and 4.20% of the population were below the poverty line, including 4.90% of those under age 18 and 4.50% of those age 65 or over.