57646 ZIP Code — Mound City, SD

Campbell County, South Dakota

ZIP code 57646 is located in Mound City, South Dakota, within Campbell County. It covers approximately 128.41 square miles and serves a population of 267 residents. This is a standard ZIP code in the Central (CT) timezone, served by area code 605.

About ZIP code 57646

The housing stock consists of predominantly single-family detached homes. Most homes were built in the pre-1940, giving the area an established character. Median home value is $109,400. Owner-occupancy is high at 94%, well above the national average.

Median household income is $91,563. The poverty rate of 6% is below the national average. 32% of households receive Social Security income, suggesting a notable retiree or disability population.

The dominant occupation class is management, business, and professional, with education and healthcare as the leading industry. The average commute of 32 minutes is near the national average. Remote work is prevalent — 44% of workers work from home.

Educational attainment is near the national average, with 39% of residents holding a bachelor's degree or higher.

Overall, ZIP code 57646 reflects a community defined by high homeownership, a high rate of remote workers, and a significant Social Security-dependent population.

267

population

128.41

sq mi land

Standard

ZIP type

Central (CT)

timezone

57646 ZIP code map

Cities in ZIP code 57646

Below are the cities the US Postal Service accepts for ZIP code 57646. Using any city not on this list may result in mail delivery delays.

City	Status
Mound City	Acceptable
Mound City	Preferred

Nearby ZIP codes

57631 Glenham (10 mi) 57632 Herreid (11.9 mi) 57648 Pollock (14.2 mi) 57472 Selby (18 mi) 57452 Java (18.5 mi) 57658 Wakpala (19.6 mi)

Demographics updated 05/2026

Population
Total population	267
Population density	2 / sq mi
State FIPS	46
County FIPS	021

Geography
Land area	128.41 sq mi
Water area	0.59 sq mi
Latitude	45.6808
Longitude	-100.1153
Timezone	Central (CT)
Area code	605

Total population by age

Gender

Race & ethnicity

Economics updated 05/2026

Household income

Income range	This ZIP	County avg	State avg
Under $50k	37.9%	42.4%	41.7%
$50k – $100k	26.6%	30.6%	33.8%
$100k – $200k	35.5%	24.7%	20.1%
Over $200k	0.0%	2.3%	4.4%

Demographics & statistics

267

Population

People per sq mi

39.1

Median age

$91,563

Median household income

$32,437

Per capita income

$109,400

Median home value

$558

Median monthly rent

93.5%

Home ownership

6.0%

Poverty rate

0.0%

Unemployment

149

Housing units

39.3%

Bachelor's or higher

Age distribution

Male Female

5–9

10–14

15–19

25–34

35–44

45–54

55–59

60–64

65–74

75–84

85+

← Male

Female →

Age summary

Group	Count	%
Under 18	77	28.8%
18 and over	190	71.2%
65 and over	45	16.9%
Median age	39.1 years

Race & ethnicity

White 89.2%

Hispanic or Latino 4.3%

Two or more races 2.9%

Other race 2.2%

American Indian / Alaska Native 1.4%

Group	Count	%
White	249	89.2%
Hispanic or Latino	12	4.3%
Two or more races	8	2.9%
Other race	6	2.2%
American Indian / Alaska Native	4	1.4%

Household income

Income range	This ZIP	County avg	State avg
Under $50k	37.9%	42.4%	41.7%
$50k – $100k	26.6%	30.6%	33.8%
$100k – $200k	35.5%	24.7%	20.1%
Over $200k	0.0%	2.3%	4.4%

Under $10k 8.3%

$15k–$25k 9.3%

$25k–$35k 7.4%

$35k–$50k 11.1%

$50k–$75k 8.3%

$75k–$100k 10.2%

$100k–$150k 15.7%

$150k–$200k 28.7%

$200k+ 0.9%

Range	% of households
Under $10k	8.3%
$15k–$25k	9.3%
$25k–$35k	7.4%
$35k–$50k	11.1%
$50k–$75k	8.3%
$75k–$100k	10.2%
$100k–$150k	15.7%
$150k–$200k	28.7%
$200k+	0.9%
Median income	$91,563

Housing

Home values

Under $50k 29.7%

$50k–$100k 15.8%

$100k–$150k 45.5%

$150k–$200k 5.0%

$200k–$300k 4.0%

Housing overview

Metric	Value
Median home value	$109,400
Median rent / month	$558
Owner occupied	93.5%
Renter occupied	6.5%
Vacant	30.8%
Single-family detached	81.4%
Large apartment buildings	0.0%
Mobile homes	17.9%
Median rooms	5.9
Avg household size (owned)	2.50

Year built

Era	%
2020 or later	0.0%
2010–2019	3.2%
2000–2009	1.9%
1990–1999	8.3%
1980–1989	0.6%
1970–1979	25.0%
1960–1969	7.7%
1950–1959	7.7%
1940–1949	5.1%
1939 or earlier	40.4%

Bedrooms

Size	% of units
No bedroom (studio)	0.0%
1 bedroom	10.3%
2 bedrooms	21.8%
3 bedrooms	35.9%
4 bedrooms	31.4%
5+ bedrooms	0.6%

Vehicles per household

Vehicles	% of households
No vehicle	0.0%
1 vehicle	6.5%
2 vehicles	27.8%
3 or more	65.7%

Heating fuel

Fuel type	%
Electricity	48.1%
Propane / LP gas	46.3%
Fuel oil	1.9%
Wood	3.7%

Households & families

Household type	Count	%
Married-couple family	87	80.6%
Cohabiting couple	3	2.8%
Male householder, no spouse	14	13.0%
Female householder, no spouse	4	3.7%
Households with children under 18	38	35.2%
Households with seniors (65+)	33	30.6%
Average household size	2.47

Marital status

Status	Male	Female
Never married	8.9%	15.0%
Married	81.1%	81.0%
Separated	0.0%	0.0%
Widowed	3.3%	3.0%
Divorced	6.7%	1.0%

Education

Less than 9th grade 4.5%

Some HS, no diploma 5.1%

HS graduate 23.6%

Some college, no degree 14.0%

Associate's degree 13.5%

Bachelor's degree 38.2%

Graduate / professional 1.1%

Metric	%
HS diploma or higher	90.4%
Bachelor's or higher	39.3%

School enrollment (ages 3–17)

Type	Count	%
Nursery / preschool	0	0.0%
Kindergarten	0	0.0%
Elementary school	59	79.7%
High school	15	20.3%
College / grad school	0	0.0%

Employment

Industry of employment

Education & healthcare 26.6%

Agriculture & mining 21.1%

Finance & real estate 18.8%

Arts, food & hospitality 9.4%

Public administration 8.6%

Construction 3.9%

Retail trade 3.9%

Wholesale trade 3.1%

Transportation & utilities 2.3%

Professional & management 1.6%

Information 0.8%

Occupation

Category	%
Management, business & arts	53.1%
Service	0.0%
Sales & office	18.0%
Natural resources & construction	11.7%
Production & transportation	17.2%

Employment type

Type	%
Private sector	54.7%
Government	36.7%
Self-employed	8.6%
Unpaid family workers	0.0%

Commute

Method	%
Drive alone	48.4%
Carpool	1.6%
Public transit	0.0%
Walk	6.3%
Work from home	43.8%
Other means	0.0%
Avg commute (minutes)	32.4

Poverty

All people 6.0%

Under 18 years 5.2%

18 and over 6.3%

Married-couple families 3.4%

Female-led households 0.0%

Income support

Source	% of households
Social Security	31.5%
Retirement income	24.1%
Supplemental Security	0.0%
Cash public assistance	0.0%
Food stamps / SNAP	0.0%

Health indicators

Condition	%
Obesity	32.4%
High blood pressure	36.5%
High cholesterol	35.4%
Diabetes	10.7%
Heart disease	8.5%
Stroke	3.6%
Asthma	8.2%
Arthritis	28.0%
Kidney disease	3.3%
Pulmonary disease	6.7%
Cancer	9.1%

Behavior / access	%
Smoking	15.9%
Binge drinking	17.5%
No physical activity	22.7%
Less than 7 hrs sleep	26.4%
Depression	13.8%
Fair or poor health	11.6%
Poor mental health	9.1%
Poor physical health	9.1%
No health insurance	10.9%
Visited doctor (checkup)	77.5%
Visited dentist	70.8%
Cholesterol screening	92.4%
Teeth loss	12.1%

Veterans & disability

Veterans	Count	%
Civilian veterans	5	2.6%

Disability	%
Any disability	4.1%
Under 18	0.0%
18–64 years	4.1%
65 and over	11.1%

Health insurance coverage

Type	%
Private insurance	88.4%
Public insurance	18.4%
No insurance	2.2%
Uninsured under 19	0.0%

Language & origin

Language spoken at home (age 5+)

Language	Count	%
English only	267	100.0%
Spanish	9	3.4%
Other Indo-European	9	3.4%
Asian & Pacific Islander	0	0.0%
Other languages	0	0.0%

Place of birth & citizenship

Origin	Count	%
Native born (US)	252	94.4%
Born in same state	252	94.4%
Born in different state	175	65.5%
Foreign born	0	0.0%
Naturalized citizen	15	5.6%
Not a US citizen	0	0.0%

Ancestry

Ancestry	Count	%
Polish	11	4.1%
Irish	8	3%
Arab	4	1.5%
German	2	0.7%

Ancestry	Count	%
English	1	0.4%
Italian	1	0.4%
French	1	0.4%

Technology access

Metric	% of households
Computer access	40.4%
Internet access	99.1%

Source: U.S. Census Bureau, American Community Survey 2025 estimates.

Frequently asked questions about ZIP code 57646

What city is ZIP code 57646 in?

ZIP code 57646 is primarily assigned to Mound City, South Dakota.

What county is ZIP code 57646 in?

ZIP code 57646 falls within Campbell County, South Dakota.

Is ZIP code 57646 mostly owner-occupied?

94% of occupied units in ZIP code 57646 are owner-occupied, well above the national average.

What is the typical home value in ZIP code 57646?

The median home value in ZIP code 57646 is $109,400.

What is the population of ZIP code 57646?

ZIP code 57646 has an estimated population of 267 residents, with a density of 2 people per square mile.

What is the median household income in ZIP code 57646?

The median household income in ZIP code 57646 is $91,563, above the national median of ~$75,000.

What timezone is ZIP code 57646 in?

ZIP code 57646 observes the CST timezone.