Sioux City (/suː/) is a city in Woodbury and Plymouth counties in the northwestern part of the U.S. state of Iowa. The population was 85,797 in the 2020 census, making it the fourth-most populous city in Iowa. The bulk of the city is in Woodbury County, of which it is the county seat, though a small northern 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. Sioux City is the primary city of the five-county Sioux City, IA–NE–SD Metropolitan Statistical Area (MSA), with a population of 149,940 in the 2020 census. The Sioux City–Vermillion, IA–NE–SD Combined Statistical Area had a population of 175,638 as of 2020.

Sioux City is at the navigational head of the Missouri River, the furthest upstream point to which general cargo ships can travel, approximately 95 mi (153 km) north of the Omaha–Council Bluffs metropolitan area. Sioux City and the surrounding areas of northwestern Iowa, northeastern Nebraska and southeastern South Dakota are sometimes referred to as Siouxland, especially by local media and residents.

Iowa is in the tallgrass prairie of the North American Great Plains, historically inhabited by speakers of Siouan languages. The area of Sioux City was inhabited by Yankton Sioux when it was first reached by Spanish and French furtrappers in the 18th century. The first documented US citizens to record their travels through this area were Meriwether Lewis and William Clark during the summer of 1804. Sergeant Charles Floyd, a member of the Lewis and Clark Expedition, died here on August 20, 1804, the only death during the two and a half-year expedition.

Sioux City was laid out in the winter of 1854–1855. It became a major transportation hub to the western Plains, including Mormons heading to Salt Lake City and speculators heading to Wyoming goldfields.

In 1891, the Sioux City Elevated Railway was opened and became the third steam-powered elevated rapid transit system in the world, and later the first electric-powered elevated railway in the world after conversion in 1892. However, the system fell into bankruptcy and closed within a decade.

The city gained the nickname "Little Chicago" during the Prohibition era due to its reputation for being a purveyor of alcoholic beverages.

On July 19, 1989, United Airlines Flight 232 crash-landed at Sioux Gateway Airport, killing 111 people, but 184 survived the crash and ensuing fire due to outstandingly quick performances by fire and emergency local teams.

According to a 2015 University of Iowa study for the Iowa Initiative for Sustainable Communities, blight and disinvestment are serious problems in the downtown core as investment has shifted to suburbs.

Sioux City borders two states, South Dakota to the west-northwest and Nebraska to the west.

According to the United States Census Bureau, the city has a total area of 59.63 sq mi (154.44 km2), of which 58.46 sq mi (151.41 km2) is land and 1.165 sq mi (3.02 km2) is water.

As is typical of Iowa, Sioux City has a humid continental climate, with very warm, humid summers, cold, dry winters, and wide temperature extremes; it is part of USDA Hardiness zone 5a. The normal monthly mean temperature ranges from 20.0 Â°F (−6.7 Â°C) in January to 74.2 Â°F (23.4 Â°C) in July. On average, there are 25 days that reach 90 Â°F (32 Â°C) or higher, 52 days that do not climb above freezing, and 17 days with a low of 0 Â°F (−18 Â°C) or below annually. The average window for freezing temperatures is October 1 through April 26, allowing a growing season of 157 days. Extreme temperatures officially range from −35 Â°F (−37 Â°C) on 12 January 1912 up to 111 Â°F (44 Â°C) on 4 July 1936 and 17 July 1936, as well as 11 July 1939; the record cold daily maximum is −22 Â°F (−30 Â°C) on 8 February 1899, while, conversely, the record warm daily minimum is 86 Â°F (30 Â°C) on 18 August 1936.

Precipitation is greatest in May and June and averages 29.27 in (743 mm) annually, but has ranged from 14.33 in (364 mm) in 1976 to 41.10 in (1,044 mm) in 1903. Snowfall averages 36.0 in (91 cm) per season, and has historically ranged from 6.9 in (18 cm) in 1895–1896 to 65.9 in (167 cm) in 1961–1962; the average window for measurable (≥0.1 in or 0.25 cm) snowfall is November 8 through April 7, although snow in October occurs several times per decade. On 14 May 2013, the high temperature reached 106 Â°F (41 Â°C), setting a new all-time May record high, along with a 77 Â°F (43 Â°C) rise from the morning of the 12th.

As of the census of 2020, there were 85,797 people. The racial makeup of the city was 76.3% White, 4.8% African American, 2.2% Native American, 2.9% Asian, 0.6% Pacific Islander, and 10.1% from other races or from two or more races. Hispanic or Latino of any race were 20.9% of the population. The city has significant minority populations of West Africans, Somalis, Ethiopians, Vietnamese, Mexicans, and Guatemalans. This has been attributed to the many meat factories and manufacturing jobs in the area.

As of the census of 2010, there were 82,684 people, 31,571 households, and 20,144 families residing in the city. The population density was 1,441.7/sq mi (556.6/km2). There were 33,425 housing units at an average density of 582.8/sq mi (225.0/km2). The racial makeup of the city was 80.6% White, 2.9% African American, 2.6% Native American, 2.7% Asian, 0.1% Pacific Islander, 7.4% from other races, and 3.7% from two or more races. Hispanic or Latino of any race were 16.4% of the population.

There were 31,571 households, of which 34.3% had children under the age of 18 living with them, 44.2% were married couples living together, 13.8% had a female householder with no husband present, 5.9% had a male householder with no wife present, and 36.2% were non-families. 29.4% of all households were made up of individuals, and 11.1% had someone living alone who was 65 years of age or older. The average household size was 2.54 and the average family size was 3.14.

The median age in the city was 33.7 years. 26.6% of residents were under the age of 18; 11.4% were between the ages of 18 and 24; 25.6% were from 25 to 44; 24% were from 45 to 64, and 12.4% were 65 years of age or older. The gender makeup of the city was 49.2% male and 50.8% female.

As of the census of 2000, there were 85,013 people, 32,054 households, and 21,091 families residing in the city. The population density was 1,551.3 inhabitants per square mile (599.0/km2). There were 33,816 housing units at an average density of 617.1 per square mile (238.3/km2). The racial makeup of the city was 85.23% White, 2.41% African American, 1.95% Native American, 2.82% Asian, 0.04% Pacific Islander, 5.27% from other races, and 2.28% from two or more races. Hispanic or Latino of any race were 10.89% of the population.

There were 32,054 households, of which 33.4% had children under the age of 18 living with them, 49.1% were married couples living together, 12.2% had a female householder with no husband present, and 34.2% were non-families. 27.7% of all households were made up of individuals, and 11.3% had someone living alone who was 65 years of age or older. The average household size was 2.57 and the average family size was 3.14.

Age spread: 27.1% under the age of 18, 11.0% from 18 to 24, 28.5% from 25 to 44, 20.2% from 45 to 64, and 13.3% who were 65 years of age or older. The median age was 33 years. For every 100 females, there were 95.4 males. For every 100 females age 18 and over, there were 92.2 males.

The median income for a household in the city was US$37,429, and the median income for a family was US$45,751. Males had a median income of US$31,385 versus US$22,470 for females. The per capita income for the city was US$18,666. About 7.9% of families and 11.2% of the population were below the poverty line, including 15.0% of those under age 18 and 7.8% of those age 65 or over. This compares with a median household income for the state of Iowa of US$54,736 and an Iowa median family income of US$69,382. (current data from State of Iowa, see also List of U.S. states by income for historical data).

As of the 2020 census, the Sioux City Metropolitan Area had 149,940 residents in four counties. As defined by the Office of Management and Budget, the counties comprising the metropolitan area are (in descending order of population):

Sioux City has a crime rate that is 91% higher than the average for Iowa and 63% higher than the national average. The violent crime rate is 90% above the Iowa average and 49% higher than the national average, based on the FBI's uniform crime reports for 2020. According to the report, this represented a 12% decrease over the prior year.

Statistics from Sioux City's 2020 Comprehensive Annual Financial Report

Golf courses, city parks, and aquatics: Sioux City is also home to several municipal public golf courses, including Floyd Park in Morningside, Green Valley near the Southern Hills, Sun Valley on the northern West Side, and Hidden Acres in nearby Plymouth County. Sioux City also has a number of private golf clubs, including Sioux City Country Club, and Whispering Creek Golf Club. The city has over 1,132 acres (5 km2) of public parkland located at 53 locations, including the riverfront and many miles of recreation trails. Five public swimming pools/aquatics centers are located within Sioux City neighborhoods.

The Sioux City Community School District served 14,569 students in the 2018-2019 school year; there are three public high schools West High School, North High School, East High School (grades 9-12), three public Middle Schools, West Middle, North Middle, and East Middle (grades 6-8), and 19 Elementary Schools (grades K-5).

Because of sprawl, districts around Sioux City continue to grow at dramatic rates. South Sioux City, Hinton, North Sioux City, Lawton, Bronson, Elk Point, Jefferson, Vermillion, Le Mars, Hawarden, Akron, Westfield, Ponca, Sergeant Bluff, Wayne, Sioux Center, along with other school districts that serve many metro-area students.

Bishop Heelan Catholic Schools is a centralized private Catholic School System that includes six schools: They teach preschool through twelfth grade.

Siouxland Christian School educates grades pre-K-12 and began in 1959.

Sioux City is home to Briar Cliff University, Morningside University, Western Iowa Tech Community College, St. Luke's College of Nursing, and the Bellevue University outreach center.

Sioux City Transit, the local public transit organization, operates several bus lines within the city. Buses transfer downtown in the Martin Luther King Jr. Transportation Center at 505 Nebraska Street. The Sioux City Paratransit serves members of the community who would otherwise not be able to travel by providing door to door service.

The city is served by Sioux Gateway Airport (SUX) 6 mi (9.7 km) to its south where United Airlines' affiliate SkyWest Airlines has announced it plans to discontinue the one flight per day each to Chicago and Denver it currently offers. As those flights are federally subsidized under the Essential Air Service program, SkyWest is required to continue those flights until a replacement is found.

FBO and jet charter services are currently offered by Hawthorne Global Aviation Services.

Jefferson Lines runs long-distance bus routes to Sioux City. Non-Transfer destinations include Winnipeg, Kansas City, Minneapolis, and Omaha.

Sioux City also has several private taxi companies that operate within the city.

There is no established water or rail passenger transportation in the area. The last passenger train was the Illinois Central's Hawkeye, a daily train to Chicago via Waterloo, Dubuque and Rockford, discontinued in 1971.