Polk City is a city in Polk County, Iowa, United States. The population was 5543 in the 2020 census, an increase from 2,344 in 2000. It is part of the Des Moines–West Des Moines Metropolitan Statistical Area.

Polk City is located along Saylorville Lake and near Big Creek State Park.

Polk City was settled in 1846 and incorporated as a city on March 13, 1875. It was an early contender for the seat of Polk County before Des Moines was ultimately chosen. The city took its name from its location in Polk County. Polk City is also known for having the only "town square" in all of Polk County.

According to the United States Census Bureau, the city has a total area of 4.47 square miles (11.58 km), of which 4.32 square miles (11.19 km) is land and 0.15 square miles (0.39 km) is water.

Historical population

Census	Pop.	Note	%±
1880	443		—
1890	446		0.7%
1900	438		−1.8%
1910	310		−29.2%
1920	277		−10.6%
1930	295		6.5%
1940	343		16.3%
1950	336		−2.0%
1960	567		68.8%
1970	715		26.1%
1980	1,658		131.9%
1990	1,908		15.1%
2000	2,344		22.9%
2010	3,418		45.8%
2020	5,543		62.2%
U.S. Decennial Census

As of the census of 2020, there were 5,543 people, 1,917 households, and 1,521 families residing in the city. The population density was 1,051.4 inhabitants per square mile (405.9/km). There were 2,015 housing units at an average density of 382.2 per square mile (147.6/km). The racial makeup of the city was 94.0% White, 0.6% Black or African American, 0.1% Native American, 0.7% Asian, 0.1% Pacific Islander, 0.4% from other races and 4.1% from two or more races. Hispanic or Latino persons of any race comprised 2.0% of the population.

Of the 1,917 households, 45.4% of which had children under the age of 18 living with them, 67.2% were married couples living together, 5.9% were cohabitating couples, 14.5% had a female householder with no spouse or partner present and 12.4% had a male householder with no spouse or partner present. 20.7% of all households were non-families. 16.1% of all households were made up of individuals, 5.0% had someone living alone who was 65 years old or older.

The median age in the city was 35.5 years. 34.2% of the residents were under the age of 20; 3.4% were between the ages of 20 and 24; 29.2% were from 25 and 44; 22.0% were from 45 and 64; and 11.2% were 65 years of age or older. The gender makeup of the city was 50.0% male and 50.0% female.

As of the census of 2010, there were 3,418 people, 1,232 households, and 957 families living in the city. The population density was 791.2 inhabitants per square mile (305.5/km). There were 1,276 housing units at an average density of 295.4 per square mile (114.1/km). The racial makeup of the city was 97.2% White, 0.8% African American, 0.2% Native American, 0.4% Asian, 0.2% from other races, and 1.1% from two or more races. Hispanic or Latino of any race were 0.9% of the population.

There were 1,232 households, of which 43.8% had children under the age of 18 living with them, 66.3% were married couples living together, 7.3% had a female householder with no husband present, 4.1% had a male householder with no wife present, and 22.3% were non-families. 17.1% of all households were made up of individuals, and 4.5% had someone living alone who was 65 years of age or older. The average household size was 2.73 and the average family size was 3.11.

The median age in the city was 34.4 years. 30.5% of residents were under the age of 18; 5.7% were between the ages of 18 and 24; 30.7% were from 25 to 44; 25.4% were from 45 to 64; and 7.7% were 65 years of age or older. The gender makeup of the city was 50.0% male and 50.0% female.

As of the census of 2000, there were 2,344 people, 826 households, and 645 families living in the city. The population density was 862.4 inhabitants per square mile (333.0/km). There were 842 housing units at an average density of 309.8 per square mile (119.6/km). The racial makeup of the city was 98.08% White, 0.30% African American, 0.26% Native American, 0.30% Asian, 0.34% from other races, and 0.73% from two or more races. Hispanic or Latino of any race were 0.68% of the population.

There were 826 households, out of which 43.2% had children under the age of 18 living with them, 70.5% were married couples living together, 5.6% had a female householder with no husband present, and 21.8% were non-families. 15.7% of all households were made up of individuals, and 5.1% had someone living alone who was 65 years of age or older. The average household size was 2.76 and the average family size was 3.15.

28.5% are under the age of 18, 6.4% from 18 to 24, 33.8% from 25 to 44, 22.8% from 45 to 64, and 8.5% who were 65 years of age or older. The median age was 34 years. For every 100 females, there were 99 males. For every 100 females age 18 and over, there were 97.3 males.

The median income for a household in the city was $58,000, and the median income for a family was $64,688. Males had a median income of $41,875 versus $27,863 for females. The per capita income for the city was $23,476, and About 2.0% of families and 2.4% of the population were below the poverty line, including 1.4% of those under age 18 and 15.6% of those aged 65 or over.

• Derald Langham (1913–1991), agricultural geneticist

North Polk Community School District serves almost all of the city. Polk City is home to North Polk West Elementary, which educates children age 3 through grade 3. Grades 4 and 5 students attend Big Creek Elementary in northeast Polk City, 6-8 graders attend the North Polk Middle school and 9-12 graders attend North Polk High School, both of which are in Alleman, which is roughly 8.5 miles away.

A small section of the city limits extends into the Ankeny Community School District.

• City of Polk City
• Polk City Chamber of Commerce