57421 ZIP Code Profile, Map, Data & Demographics

ZIP Code Type: STANDARD
County: Marshall County
Centroid: Latitude 45.717, Longitude -97.92
Time Zone: Central Time Zone (UTC -6 hours)
Observes DST: Yes

ZIP Code 57421 has segments in 2 Counties (Brown, Marshall).

Businesses Addresses: 5
PO Box Addresses: 9
Residential Addresses: 22

Multi-Family Addresses: 0
Single Family Addresses: 22

The ZIP Code maps and database are updated 4 times per year.
Database updated: June 1, 2025, Maps updated: May 1, 2024.

Amherst, SD 57421 Data & Demographics (As of July 1, 2025)

POPULATION
Total Population	177 (100%)
Population in Households	59 (33.3%)
Population in Families	55 (31.1%)
Population in Group Quarters¹	118 (66.7%)
Population Density	6
Diversity Index²	15


INCOME
Median Household Income	$103,313
Average Household Income	$130,302
% of Income for Mortgage⁴	0%
Per Capita Income	$17,896
Wealth Index⁵	131
Socioeconomic Status Index⁶	High (68.1)

HOUSING
Total HU (Housing Units)	28 (100%)
Owner Occupied HU	16 (57.1%)
Renter Occupied HU	5 (17.9%)
Vacant Housing Units	7 (25.0%)
Median Home Value	$325,000
Average Home Value	$420,781
Housing Affordability Index³	0

HOUSEHOLDS
Total Households	21
Average Household Size	2.81
Family Households	18
Average Family Size	3.00

NOTES

Group Quarters - a place where people live or stay in a group living arrangement. Includes college residents halls, nursing facilities, military barracks, and correctional facilities.
The Diversity Index is a scale of 0 to 100 that represents the likelihood that two persons, chosen at random from the same area, belong to different races or ethnic groups. If an area's entire population belongs to one race AND one ethnic group, then the area has zero diversity. An area's diversity index increases to 100 when the population is evenly divided into two or more race/ethnic groups.
The Housing Affordability Index base is 100 and represents a balance point where a resident with a median household income can normally qualify to purchase a median price home. Values above 100 indicate increased affordability, while values below 100 indicate decreased affordability.
The % of Income for Mortgage quantifies the percentage of median household income dedicated to mortgage payments on a home priced at the median value (assuming a 30-year mortgage and a 20% down payment).
The Wealth Index is based on a number of indicators of affluence including average household income and average net worth, but it also includes the value of material possessions and resources. It represents the wealth of the area relative to the national level. Values above or below 100 represent above-average wealth or below-average wealth compared to the national level.
The Socioeconomic Index ranges from zero (lowest relative status) to 100 (highest relative status). This measure quantifies disparities in social position of an area's inhabitants and is built from a broad range of demographic, housing, and socioeconomic inputs. More information on this measure can be found in Esri's SEI tutorial.

Amherst, SD 57421 - Peer Comparisons by Rank and Percentile

The table below compares 57421 to the other 371 ZIP Codes in South Dakota by rank and percentile using July 1, 2025 data. The location Ranked # 1 has the highest value. A location that ranks higher than 75% of its peers would be in the 75th percentile of the peer group.

GROWTH RATE / YEAR	2020-2025	2025-2030
Population	0.22%	0.78%
Households	-1.72%	1.84%
Families		0.00%
Median Household Income		-3.65%
Per Capita Income		3.14%
Owner Occupied HU		6.58%

Variable Description	Rank	Percentile
Total Population	# 313	16th
Population Density	# 161	57th
Median Household Income	# 27	93rd
Housing Affordability Index	# 57	15th
Per Capita Income	# 349	6th
Diversity Index	# 288	23rd

57421 ZIP Code Profile, Map, Data & Demographics

ZIP Code 57421: Basic Data & USPS Preferred City Name

Amherst, SD 57421 Data & Demographics (As of July 1, 2025)

POPULATION

INCOME

HOUSING

HOUSEHOLDS

GROWTH RATE / YEAR

Amherst, SD 57421 - Peer Comparisons by Rank and Percentile

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