Anoka County is the fourth-most populous county in the U.S. state of Minnesota. As of the 2020 census, its population was 363,887. The county seat and namesake of the county is the city of Anoka, which is derived from the Dakota word anoka meaning "on both sides", referring to its location on both banks of the Rum River. The largest city in the county is Blaine, the tenth-largest city in Minnesota and the sixth-largest Twin Cities suburb.