57421 ZIP Code — Amherst, SD
Marshall County, South Dakota
ZIP code 57421 is located in Amherst, South Dakota, within Marshall County. It covers approximately 33.34 square miles and serves a population of 54 residents. This is a standard ZIP code in the Central (CT) timezone, served by area code 605.
54
population
33.34
sq mi land
Standard
ZIP type
Central (CT)
timezone
57421 ZIP code map
Cities in ZIP code 57421
Below are the cities the US Postal Service accepts for ZIP code 57421. Using any city not on this list may result in mail delivery delays.
| City | Status |
|---|---|
| Amherst | Acceptable |
Demographics
updated 06/2026
| Population | |
|---|---|
| Total population | 54 |
| Population density | 2 / sq mi |
| State FIPS | 46 |
| County FIPS | 091 |
| Geography | |
|---|---|
| Land area | 33.34 sq mi |
| Water area | 0.09 sq mi |
| Latitude | 45.7333 |
| Longitude | -97.9170 |
| Timezone | Central (CT) |
| Area code | 605 |
Total population by age
Gender
Race & ethnicity
Economics
updated 06/2026
Household income
| Income range | This ZIP | County avg | State avg |
|---|---|---|---|
| Under $50k | 0.0% | 34.6% | 41.7% |
| $50k – $100k | 0.0% | 39.5% | 33.8% |
| $100k – $200k | 100.0% | 20.8% | 20.1% |
| Over $200k | 0.0% | 5.1% | 4.4% |
Demographics & statistics
54
Population
2
People per sq mi
11.1
Median age
$0
Median household income
$22,704
Per capita income
$0
Median home value
$0
Median monthly rent
100.0%
Home ownership
0.0%
Poverty rate
0.0%
Unemployment
10
Housing units
90.0%
Bachelor's or higher
Age distribution
Male
Female
9
5–9
17
3
10–14
5
5
35–44
11
1
60–64
1
1
65–74
1
← Male
Female →
Age summary
| Group | Count | % |
|---|---|---|
| Under 18 | 34 | 63.0% |
| 18 and over | 20 | 37.0% |
| 65 and over | 2 | 3.7% |
| Median age | 11.1 years | |
Race & ethnicity
White
100%
| Group | Count | % |
|---|---|---|
| White | 54 | 100% |
Household income
| Income range | This ZIP | County avg | State avg |
|---|---|---|---|
| Under $50k | 0.0% | 34.6% | 41.7% |
| $50k – $100k | 0.0% | 39.5% | 33.8% |
| $100k – $200k | 100.0% | 20.8% | 20.1% |
| Over $200k | 0.0% | 5.1% | 4.4% |
$75k–$100k
20.0%
$100k–$150k
80.0%
| Range | % of households |
|---|---|
| $75k–$100k | 20.0% |
| $100k–$150k | 80.0% |
| Median income | $0 |
Housing
Home values
$150k–$200k
80.0%
$200k–$300k
20.0%
Housing overview
| Metric | Value |
|---|---|
| Median home value | $0 |
| Median rent / month | $0 |
| Owner occupied | 100.0% |
| Renter occupied | 0.0% |
| Vacant | 0.0% |
| Single-family detached | 100.0% |
| Large apartment buildings | 0.0% |
| Mobile homes | 0.0% |
| Median rooms | 0.0 |
| Avg household size (owned) | 5.40 |
Year built
| Era | % |
|---|---|
| 2020 or later | 0.0% |
| 2010–2019 | 0.0% |
| 2000–2009 | 0.0% |
| 1990–1999 | 0.0% |
| 1980–1989 | 0.0% |
| 1970–1979 | 20.0% |
| 1960–1969 | 0.0% |
| 1950–1959 | 0.0% |
| 1940–1949 | 0.0% |
| 1939 or earlier | 80.0% |
Bedrooms
| Size | % of units |
|---|---|
| No bedroom (studio) | 0.0% |
| 1 bedroom | 0.0% |
| 2 bedrooms | 0.0% |
| 3 bedrooms | 0.0% |
| 4 bedrooms | 80.0% |
| 5+ bedrooms | 20.0% |
Vehicles per household
| Vehicles | % of households |
|---|---|
| No vehicle | 0.0% |
| 1 vehicle | 0.0% |
| 2 vehicles | 0.0% |
| 3 or more | 100.0% |
Heating fuel
| Fuel type | % |
|---|---|
| Propane / LP gas | 100.0% |
Households & families
| Household type | Count | % |
|---|---|---|
| Married-couple family | 10 | 100.0% |
| Cohabiting couple | 0 | 0.0% |
| Male householder, no spouse | 0 | 0.0% |
| Female householder, no spouse | 0 | 0.0% |
| Households with children under 18 | 8 | 80.0% |
| Households with seniors (65+) | 2 | 20.0% |
| Average household size | 5.40 | |
Marital status
| Status | Male | Female |
|---|---|---|
| Never married | 0.0% | 0.0% |
| Married | 100.0% | 100.0% |
| Separated | 0.0% | 0.0% |
| Widowed | 0.0% | 0.0% |
| Divorced | 0.0% | 0.0% |
Education
Less than 9th grade
0.0%
Some HS, no diploma
0.0%
HS graduate
0.0%
Some college, no degree
0.0%
Associate's degree
10.0%
Bachelor's degree
40.0%
Graduate / professional
50.0%
| Metric | % |
|---|---|
| HS diploma or higher | 100.0% |
| Bachelor's or higher | 90.0% |
School enrollment (ages 3–17)
| Type | Count | % |
|---|---|---|
| Nursery / preschool | 13 | 38.2% |
| Kindergarten | 0 | 0.0% |
| Elementary school | 21 | 61.8% |
| High school | 0 | 0.0% |
| College / grad school | 0 | 0.0% |
Employment
Industry of employment
Education & healthcare
50.0%
Other services
50.0%
Occupation
| Category | % |
|---|---|
| Management, business & arts | 100.0% |
| Service | 0.0% |
| Sales & office | 0.0% |
| Natural resources & construction | 0.0% |
| Production & transportation | 0.0% |
Employment type
| Type | % |
|---|---|
| Private sector | 50.0% |
| Government | 50.0% |
| Self-employed | 0.0% |
| Unpaid family workers | 0.0% |
Commute
| Method | % |
|---|---|
| Drive alone | 0.0% |
| Carpool | 0.0% |
| Public transit | 0.0% |
| Walk | 0.0% |
| Work from home | 100.0% |
| Other means | 0.0% |
| Avg commute (minutes) | 0.0 |
Poverty
All people
0.0%
Under 18 years
0.0%
18 and over
0.0%
Married-couple families
0.0%
Female-led households
0.0%
Income support
| Source | % of households |
|---|---|
| Social Security | 0.0% |
| Retirement income | 20.0% |
| Supplemental Security | 0.0% |
| Cash public assistance | 0.0% |
| Food stamps / SNAP | 0.0% |
Health indicators
| Condition | % |
|---|---|
| Obesity | 31.6% |
| High blood pressure | 32.5% |
| High cholesterol | 32.6% |
| Diabetes | 9.4% |
| Heart disease | 7.6% |
| Stroke | 3.3% |
| Asthma | 8.5% |
| Arthritis | 25.5% |
| Kidney disease | 3.1% |
| Pulmonary disease | 6.2% |
| Cancer | 8.2% |
| Behavior / access | % |
|---|---|
| Smoking | 15.7% |
| Binge drinking | 20.1% |
| No physical activity | 21.9% |
| Less than 7 hrs sleep | 26.0% |
| Depression | 14.7% |
| Fair or poor health | 11.0% |
| Poor mental health | 10.1% |
| Poor physical health | 8.8% |
| No health insurance | 11.3% |
| Visited doctor (checkup) | 75.5% |
| Visited dentist | 68.3% |
| Cholesterol screening | 89.0% |
| Teeth loss | 12.4% |
Veterans & disability
| Veterans | Count | % |
|---|---|---|
| Civilian veterans | 0 | 0.0% |
| Disability | % |
|---|---|
| Any disability | 0.0% |
| Under 18 | 0.0% |
| 18–64 years | 0.0% |
| 65 and over | 0.0% |
Health insurance coverage
| Type | % |
|---|---|
| Private insurance | 100.0% |
| Public insurance | 3.7% |
| No insurance | 0.0% |
| Uninsured under 19 | 0.0% |
Language & origin
Language spoken at home (age 5+)
| Language | Count | % |
|---|---|---|
| English only | 54 | 100.0% |
| Spanish | 0 | 0.0% |
| Other Indo-European | 0 | 0.0% |
| Asian & Pacific Islander | 0 | 0.0% |
| Other languages | 0 | 0.0% |
Place of birth & citizenship
| Origin | Count | % |
|---|---|---|
| Native born (US) | 54 | 100.0% |
| Born in same state | 54 | 100.0% |
| Born in different state | 17 | 31.5% |
| Foreign born | 0 | 0.0% |
| Naturalized citizen | 0 | 0.0% |
| Not a US citizen | 0 | 0.0% |
Ancestry
| Ancestry | Count | % |
|---|---|---|
| Italian | 42 | 77.8% |
| Ancestry | Count | % |
|---|---|---|
| Polish | 2 | 3.7% |
Technology access
| Metric | % of households |
|---|---|
| Computer access | 18.5% |
| Internet access | 100.0% |
Source: U.S. Census Bureau, American Community Survey 2025 estimates.
Frequently asked questions about ZIP code 57421
What city is ZIP code 57421 in?
ZIP code 57421 is primarily assigned to Amherst, South Dakota.
What county is ZIP code 57421 in?
ZIP code 57421 falls within Marshall County, South Dakota.
Is ZIP code 57421 family-oriented?
63% of residents in ZIP code 57421 are under 18, reflecting a younger, family-oriented community.
How educated is the population of ZIP code 57421?
90% of residents hold a bachelor's degree or higher — well above the national average of ~33%, reflecting a highly educated population.
What is the population of ZIP code 57421?
ZIP code 57421 has an estimated population of 54 residents, with a density of 2 people per square mile.
What timezone is ZIP code 57421 in?
ZIP code 57421 observes the CST timezone.