County outline
Where Custer County is located
Area breakdown
Land accounts for 99.9% of Custer County’s measured area and water for 0.1%. Its combined area converts to 4,038 square kilometers or approximately 997,800 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 1,556.943 | 4,032.464 | 996,443.5 |
| Water | 2.12 | 5.491 | 1,356.8 |
| Total | 1,559.063 | 4,037.955 | 997,800.3 |
How Custer County compares
By original Census land area, Custer County ranks #16 of 66 in South Dakota and #388 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.712 times the South Dakota county-equivalent median of 909.3 square miles. It accounts for 2.1% of the combined county land area in the state.
See the complete South Dakota ranking · What counts as a county equivalent?
What stands out about Custer County?
Custer County has more land than 2,834 of the other 3,221 county equivalents in the dataset.
A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.
Does including water change its rank?
Using land plus water places Custer County at #428 nationally by total area, 40 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.
Its water share is 0.1%, compared with a national county-equivalent median of 1.2% — 1 percentage points lower. This describes the statistical geography’s land/water mix, not flood exposure or developable land.
Closest positions in the national land ranking
These entries sit immediately beside Custer County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #387 | Chippewa County, Michigan | 1,558.5 | Compare |
| #388 | Custer County, South Dakota | 1,556.9 | This county |
| #389 | Uvalde County, Texas | 1,551.9 | Compare |
Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.
Representative coordinates
The Census internal point is 43.685292, -103.437000. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.
Source and precision
U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 4,032,464,151 m²; AWATER: 5,490,769 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.
Common questions
How many acres of land are in Custer County?
The land measurement converts to approximately 996,444 acres. Including water, total area is approximately 997,800 acres. One square mile equals 640 acres.
Why might another source show a different area?
Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.
Can this establish a property boundary?
No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.