57440 ZIP Code — Frankfort, SD

Spink County, South Dakota

ZIP code 57440 is located in Frankfort, South Dakota, within Spink County. It covers approximately 141.93 square miles and serves a population of 506 residents. This is a standard ZIP code in the Central (CT) timezone, served by area code 605.

About ZIP code 57440

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 $82,000. Owner-occupancy is high at 88%, well above the national average.

The gap between median ($54,375) and mean household income suggests income inequality — a small number of higher earners pull the average up. 33% of households receive Social Security income, suggesting a notable retiree or disability population.

The dominant occupation class is production, transportation, and material moving, with agriculture and mining as the leading industry. The average commute of 21 minutes is near the national average. Remote work is prevalent — 22% of workers work from home.

College attainment at 12% is below the national average, consistent with a trades and production-oriented local economy.

Overall, ZIP code 57440 reflects a community defined by a trades-oriented workforce, high homeownership, a high rate of remote workers, and a significant Social Security-dependent population.

506
population
141.93
sq mi land
Standard
ZIP type
Central (CT)
timezone
57440 ZIP code map
Cities in ZIP code 57440

Below are the cities the US Postal Service accepts for ZIP code 57440. Using any city not on this list may result in mail delivery delays.

City Status
Frankfort Acceptable
Frankfort Preferred
Nearby ZIP codes
57436 Doland (8.4 mi) 57469 Redfield (15.1 mi) 57477 Turton (15.3 mi) 57348 Hitchcock (15.7 mi) 57258 Raymond (16.8 mi) 57424 Ashton (17 mi) 57476 Tulare (18.6 mi)
Demographics updated 05/2026
Population
Total population 506
Population density 4 / sq mi
State FIPS 46
County FIPS 115
Geography
Land area 141.93 sq mi
Water area 0.69 sq mi
Latitude 44.8359
Longitude -98.2524
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 34.4% 39.1% 41.7%
$50k – $100k 34.4% 33.1% 33.8%
$100k – $200k 12.3% 20.0% 20.1%
Over $200k 18.8% 7.8% 4.4%

Demographics & statistics

506
Population
4
People per sq mi
43.7
Median age
$54,375
Median household income
$37,218
Per capita income
$82,000
Median home value
$0
Median monthly rent
87.8%
Home ownership
16.6%
Poverty rate
5.9%
Unemployment
164
Housing units
12.3%
Bachelor's or higher

Age distribution

Male Female
4
Under 5
5
7
10–14
7
23
15–19
26
29
20–24
31
33
25–34
36
35
35–44
39
23
45–54
26
25
55–59
27
22
60–64
23
18
65–74
19
20
75–84
21
3
85+
4
← Male
Female →

Age summary

GroupCount%
Under 18458.9%
18 and over46191.1%
65 and over8516.8%
Median age43.7 years

Race & ethnicity

White 99.6%
Hispanic or Latino 0.2%
Other race 0.2%
GroupCount%
White50599.6%
Hispanic or Latino10.2%
Other race10.2%

Household income

Income range This ZIP County avg State avg
Under $50k 34.4% 39.1% 41.7%
$50k – $100k 34.4% 33.1% 33.8%
$100k – $200k 12.3% 20.0% 20.1%
Over $200k 18.8% 7.8% 4.4%
Under $10k 6.5%
$10k–$15k 2.9%
$15k–$25k 6.5%
$25k–$35k 8.6%
$35k–$50k 23.0%
$50k–$75k 20.1%
$75k–$100k 7.9%
$100k–$150k 7.9%
$200k+ 16.5%
Range% of households
Under $10k6.5%
$10k–$15k2.9%
$15k–$25k6.5%
$25k–$35k8.6%
$35k–$50k23.0%
$50k–$75k20.1%
$75k–$100k7.9%
$100k–$150k7.9%
$200k+16.5%
Median income$54,375

Housing

Home values

Under $50k 25.4%
$50k–$100k 32.8%
$100k–$150k 14.8%
$150k–$200k 4.1%
$200k–$300k 19.7%
$300k–$500k 0.8%
$500k–$1M 2.5%

Housing overview

MetricValue
Median home value$82,000
Median rent / month$0
Owner occupied87.8%
Renter occupied12.2%
Vacant23.2%
Single-family detached78.5%
Large apartment buildings0.0%
Mobile homes12.2%
Median rooms7.3
Avg household size (owned)3.50

Year built

Era%
2020 or later0.0%
2010–20195.5%
2000–20096.6%
1990–199916.0%
1980–19894.4%
1970–19793.9%
1960–19691.1%
1950–19595.5%
1940–19492.8%
1939 or earlier54.1%

Bedrooms

Size% of units
No bedroom (studio)0.0%
1 bedroom2.2%
2 bedrooms34.8%
3 bedrooms25.4%
4 bedrooms22.7%
5+ bedrooms14.9%

Vehicles per household

Vehicles% of households
No vehicle0.0%
1 vehicle37.4%
2 vehicles30.2%
3 or more32.4%

Heating fuel

Fuel type%
Utility gas38.8%
Electricity41.7%
Propane / LP gas12.2%
Fuel oil2.9%
No fuel used4.3%

Households & families

Household typeCount%
Married-couple family6848.9%
Cohabiting couple42.9%
Male householder, no spouse2618.7%
Female householder, no spouse4129.5%
Households with children under 184330.9%
Households with seniors (65+)5438.8%
Average household size3.30

Marital status

StatusMaleFemale
Never married33.0%47.6%
Married48.1%34.4%
Separated0.0%0.0%
Widowed0.9%16.0%
Divorced18.0%2.0%

Education

Less than 9th grade 24.3%
Some HS, no diploma 8.8%
HS graduate 26.2%
Some college, no degree 20.9%
Associate's degree 7.5%
Bachelor's degree 9.6%
Graduate / professional 2.7%
Metric%
HS diploma or higher66.8%
Bachelor's or higher12.3%

School enrollment (ages 3–17)

TypeCount%
Nursery / preschool47.5%
Kindergarten00.0%
Elementary school917.0%
High school2037.7%
College / grad school2037.7%

Employment

Industry of employment

Agriculture & mining 32.1%
Other services 12.5%
Construction 11.2%
Manufacturing 9.8%
Finance & real estate 9.4%
Education & healthcare 8.5%
Retail trade 7.1%
Wholesale trade 2.7%
Transportation & utilities 2.7%
Arts, food & hospitality 2.7%
Professional & management 0.9%
Public administration 0.4%

Occupation

Category%
Management, business & arts27.7%
Service2.7%
Sales & office23.2%
Natural resources & construction16.5%
Production & transportation29.9%

Employment type

Type%
Private sector65.2%
Government6.7%
Self-employed18.8%
Unpaid family workers9.4%

Commute

Method%
Drive alone52.7%
Carpool2.7%
Public transit0.0%
Walk23.0%
Work from home21.6%
Other means0.0%
Avg commute (minutes)21.4

Poverty

All people 16.6%
Under 18 years 8.9%
18 and over 17.4%
Married-couple families 5.9%
Female-led households 0.0%

Income support

Source% of households
Social Security33.1%
Retirement income18.0%
Supplemental Security6.5%
Cash public assistance0.0%
Food stamps / SNAP0.0%

Health indicators

Condition%
Obesity35.0%
High blood pressure31.2%
High cholesterol31.9%
Diabetes9.3%
Heart disease7.4%
Stroke3.3%
Asthma8.8%
Arthritis24.3%
Kidney disease3.0%
Pulmonary disease6.6%
Cancer7.5%
Behavior / access%
Smoking18.8%
Binge drinking20.2%
No physical activity24.1%
Less than 7 hrs sleep27.6%
Depression16.0%
Fair or poor health12.3%
Poor mental health11.0%
Poor physical health9.2%
No health insurance14.2%
Visited doctor (checkup)73.2%
Visited dentist65.9%
Cholesterol screening87.3%
Teeth loss15.1%

Veterans & disability

VeteransCount%
Civilian veterans4910.6%
Disability%
Any disability6.3%
Under 180.0%
18–64 years0.3%
65 and over36.5%

Health insurance coverage

Type%
Private insurance89.7%
Public insurance20.0%
No insurance2.6%
Uninsured under 190.0%

Language & origin

Language spoken at home (age 5+)

LanguageCount%
English only49798.2%
Spanish91.8%
Other Indo-European00.0%
Asian & Pacific Islander71.4%
Other languages00.0%

Place of birth & citizenship

OriginCount%
Native born (US)50399.4%
Born in same state50399.4%
Born in different state40379.6%
Foreign born00.0%
Naturalized citizen30.6%
Not a US citizen3100.0%

Ancestry

AncestryCount%
Polish6713.2%
Arab204%
Italian183.6%
AncestryCount%
Irish102%
French102%

Technology access

Metric% of households
Computer access27.5%
Internet access87.8%

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

Frequently asked questions about ZIP code 57440

What city is ZIP code 57440 in?

ZIP code 57440 is primarily assigned to Frankfort, South Dakota.

What county is ZIP code 57440 in?

ZIP code 57440 falls within Spink County, South Dakota.

Is ZIP code 57440 mostly owner-occupied?

88% of occupied units in ZIP code 57440 are owner-occupied, well above the national average.

How educated is the population of ZIP code 57440?

12% of residents hold a bachelor's degree or higher — below the national average of ~33%, consistent with a trades-oriented local economy.

What is the poverty rate in ZIP code 57440?

17% of residents in ZIP code 57440 live below the poverty line, above the national average.

Does ZIP code 57440 have a large veteran population?

11% of civilians in ZIP code 57440 are veterans, above the national average of ~7%.

What timezone is ZIP code 57440 in?

ZIP code 57440 observes the CST timezone.

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