View source for Sergeant Bluff, Iowa

===2020 census===
As of the [[2020 United States census|2020 census]], Sergeant Bluff had a population of 5,015, with 1,731 households and 1,312 families. The median age was 37.2 years. 28.3% of residents were under the age of 18 and 14.4% of residents were 65 years of age or older. For every 100 females there were 96.4 males, and for every 100 females age 18 and over there were 93.6 males age 18 and over.<ref name="Census2020DP">{{cite web|title=2020 Decennial Census Demographic Profile (DP1)|url=https://api.census.gov/data/2020/dec/dp?get=NAME,DP1_0021P,DP1_0024P,DP1_0025C,DP1_0049C,DP1_0045C,DP1_0069C,DP1_0073C,DP1_0125P,DP1_0126P,DP1_0129P,DP1_0133P,DP1_0137P,DP1_0138P,DP1_0139P,DP1_0141P,DP1_0142P,DP1_0143P,DP1_0145P,DP1_0146P,DP1_0147C,DP1_0148C,DP1_0149C,DP1_0156C,DP1_0157C,DP1_0158C,DP1_0159P,DP1_0160P&for=place%3A71625&in=state%3A19|website=United States Census Bureau|year=2021|access-date=April 28, 2026|df=mdy}}</ref><ref name="Census2020PL">{{cite web|title=2020 Decennial Census Redistricting Data (Public Law 94-171)|url=https://api.census.gov/data/2020/dec/pl?get=NAME,P1_001N,P1_003N,P1_004N,P1_005N,P1_006N,P1_007N,P1_008N,P1_009N,P2_001N,P2_002N,H1_001N,H1_002N&for=place%3A71625&in=state%3A19|website=United States Census Bureau|year=2021|access-date=April 28, 2026|df=mdy}}</ref>

99.9% of residents lived in urban areas, while 0.1% lived in rural areas.<ref name="Census2020DHC">{{cite web|title=2020 Decennial Census Demographic and Housing Characteristics (DHC)|url=https://api.census.gov/data/2020/dec/dhc?get=NAME,P2_002N,P2_003N&for=place%3A71625&in=state%3A19|website=United States Census Bureau|year=2023|access-date=April 28, 2026|df=mdy}}</ref>

Of the 1,731 households, 40.5% had children under the age of 18 living in them. Of all households, 58.8% were married-couple households, 8.5% were cohabiting-couple households, 13.9% were households with a male householder and no spouse or partner present, and 18.9% were households with a female householder and no spouse or partner present. Non-families made up 24.2% of all households. About 18.8% of all households were made up of individuals and 9.0% had someone living alone who was 65 years of age or older.<ref name="Census2020DP"/>

There were 1,822 housing units, of which 5.0% were vacant. The homeowner vacancy rate was 0.7% and the rental vacancy rate was 7.4%. The population density was 1,687.4 inhabitants per square mile (651.5/km<sup>2</sup>), and there were 613.1 housing units per square mile (236.7/km<sup>2</sup>).<ref name="Census2020DP"/><ref>{{cite web |title=2020 Census |url=https://www.census.gov/programs-surveys/decennial-census/decade/2020/2020-census-main.html |publisher=United States Census Bureau}}</ref>

{| class="wikitable"
|+ Racial composition as of the 2020 census<ref name="Census2020PL"/>
! Race !! Number !! Percent
|-
| [[White Americans|White]] || 4,327 || 86.3%
|-
| [[African Americans|Black or African American]] || 81 || 1.6%
|-
| [[Native Americans in the United States|American Indian and Alaska Native]] || 54 || 1.1%
|-
| [[Asian Americans|Asian]] || 141 || 2.8%
|-
| [[Native Hawaiians|Native Hawaiian]] and [[Pacific Islander|Other Pacific Islander]] || 5 || 0.1%
|-
| Some other race || 91 || 1.8%
|-
| [[Multiracial Americans|Two or more races]] || 316 || 6.3%
|-
| ''[[Hispanic and Latino Americans|Hispanic or Latino]] (of any race)'' || 319 || 6.4%
|}