Sioux City () is a city in Woodbury and Plymouth counties in the northwestern part of the U.S. state of Iowa. The population was 82,684 in the 2010 census, which makes it the fourth-largest city in Iowa. The bulk of the city is in Woodbury County, of which it is the county seat, though a small portion is in Plymouth County. Sioux City is located at the navigational head of the Missouri River. The city is home to several cultural points of interest including the Sioux City Public Museum, Sioux City Art Center and Sergeant Floyd Monument, which is a National Historic Landmark. The city is also home to Chris Larsen Park, commonly referred to as "the Riverfront", which includes the Anderson Dance Pavilion, Sergeant Floyd Riverboat Museum and Lewis and Clark Interpretive Center.