The Sioux City Metropolitan Statistical Area, otherwise known as Siouxland, as defined by the United States Census Bureau, is an area consisting of four counties in three states – Iowa, Nebraska, and South Dakota, anchored by the city of Sioux City, Iowa. As of the 2000 census, the MSA had a population of 143,005 (though a July 1, 2009 estimate placed the population at 144,360).