Minneapolis, nicknamed "City of Lakes" and the "Mill City," is the county seat of Hennepin County, the largest city in the U.S. state of Minnesota, and the 48th largest in the United States. Its name is attributed to the city's first schoolteacher, who combined mni, the Dakota word for water, and polis, the Greek word for city. Minneapolis lies on both banks of the Mississippi River, just north of the river's confluence with the Minnesota River, and adjoins Saint Paul, the state's capital. Known as the "Twin Cities," Minneapolis-St. Paul is the 16th-largest metropolitan area in the U.S., with 3.5 million residents. The Metropolitan Council estimated the city's population in 2008 as 390,131.