Sweetwater County area

Population and density of Sweetwater County

The Census Bureau estimates that 41,267 people lived in Sweetwater County on July 1, 2025. That ranks #1,189 of 3,222 county equivalents nationally and #4 of 23 in Wyoming. Since the April 1, 2020 estimates base of 42,268, the population has declined by 1,001 (−2.4%), compared with +2.1% for Wyoming as a whole.

With 10,427 square miles of land, that is 4 people per square mile (1.5 per km²), placing Sweetwater County #2,911 nationally for density and #13 in Wyoming. The median county equivalent has 47 people per square mile; the Wyoming median is 4.1. Put another way, there are about 162 acres of land per resident.

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Sweetwater County

6 incorporated places lie at least partly in Sweetwater County. Together they are home to 34,926 people (84.6%); the other 6,341 (15.4%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Rock Springs city, with 22,936 residents in the county. The county seat, Green River city, has 11,450 residents.

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Sweetwater County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.

Metropolitan area

Sweetwater County is a central county of the Rock Springs, WY Micropolitan Statistical Area. Sweetwater County is the area’s only county equivalent, so the micro area has the same 10,427 square miles of land. By combined land it ranks #3 of 542 micropolitan areas, and #310 by population.

ZIP codes

12 ZIP Code Tabulation Areas have land in Sweetwater County; 11 of them have most of their land inside the county, and the others mainly cover neighboring areas.

823018232282336829018292982932829348293582938829428294382945

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.

Counties bordering Sweetwater County

Sweetwater County shares a land border with 8 county equivalents, including 3 in Colorado and Utah. It has more land than every one of them. The largest neighbor is Fremont County (9,183.6 mi²) and the smallest is Daggett County (696.5 mi²). Together with its neighbors, Sweetwater County forms a block of 45,862.3 mi² of land, of which it holds 22.7%.

How big is Sweetwater County compared with U.S. states?

Sweetwater County has more land than 9 of the 50 states. It is about 1.1 times the land area of Maryland (9,711 mi²), while West Virginia, the next larger state, has 2.3 times as much land (24,041.4 mi²). Wyoming’s county land could hold about 9.3 areas the size of Sweetwater County.

Another way to picture it: the same land area would fill a square about 102.1 miles (164.3 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Sweetwater County?

Sweetwater County has more land than 3,201 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 Sweetwater County at #26 nationally by total area, 5 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 0.6%, compared with a national county-equivalent median of 1.2% — 0.6 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 Sweetwater County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

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.