🇺🇸 United States ZIP Code

STANDARD

57751

Keystone

ZIP Code 57751 is a standard zip code serving Keystone, Keystone, South Dakota (SD), in Pennington County, United States. It has an estimated population of 844 with a median household income of $49,274. The area falls within the America/Denver timezone.

Median Household Income vs. National Average

Location

Country: 🇺🇸 United States
State / Province: South Dakota (SD)
County: Pennington
City: Keystone
Timezone: America/Denver

Coordinates

Latitude: 43.884800
Longitude: -103.399500

Geographic Details

Land Area: 68.21 mi²
Water Area: 0.04 mi²
Population Density: 12.0 people per mi² (15th percentile)
Bounding Box: 43.929961°N, 43.760075°S, -103.216624°E, -103.511058°W

With 844 residents spread across 68.21 square miles, this area has a population density of 12.0 people per square mile.

Demographics

844

Population

20th percentile

$49,274

Median Income

50th percentile

$175,500

Median Home Value

65th percentile

68.21 mi²

Land Area

The median household income in 57751 is $49,274, and the median home value is $175,500.

Housing

556

Total Units

375

Occupied Units

67.4%

Occupancy Rate

Similar ZIP Codes in South Dakota

ZIP codes with similar median household income in South Dakota.

57301

Mitchell

$47,962

57760

Newell

$45,250

57328

Corsica

$54,688

57012

Canistota

$56,136

57066

Tyndall

$43,077

57790

Wall

$48,550

57279

Wilmot

$43,250

57345

Highmore

$48,438

Frequently Asked Questions

What information is available for each ZIP code?

Each ZIP code page shows city, state, county, geographic coordinates, timezone, population, median household income, median home value, housing units, land area, population density, commute time, educational attainment, area codes, and ZIP code type (Standard, PO Box, or Unique).

What are the different types of ZIP codes?

There are three types of ZIP codes: Standard (residential and commercial delivery areas), PO Box (assigned to post office box sections), and Unique (assigned to a single high-volume address like a government agency or large company). Standard ZIP codes are the most common.

How often is ZIP code data updated?

ZIP code assignments are updated quarterly by the USPS. Demographic data comes from the US Census Bureau's American Community Survey (ACS), which releases new 5-year estimates annually. ZipFYI updates its data to reflect the latest available information.

What is population density and why does it matter?

Population density measures the number of people per square mile in a ZIP code area. It helps identify urban vs. rural areas, affects real estate values, impacts service availability, and is used in market analysis. Dense urban ZIP codes may have 50,000+ people per square mile.

How are ZIP code boundaries determined?

ZIP code boundaries are determined by the USPS based on mail delivery routes, not political or geographic boundaries. They follow carrier routes and may cross city, county, or even state lines. Boundaries can change when the USPS reorganizes delivery operations.

What does median household income tell me about a ZIP code?

Median household income is the middle value when all household incomes in a ZIP code are sorted. Half of households earn more and half earn less. It is a better indicator of typical earnings than average income, which can be skewed by very high or very low outliers.