County outline
Where Natrona County is located
Area breakdown
Land accounts for 99.3% of Natrona County’s measured area and water for 0.7%. Its combined area converts to 13,922.9 square kilometers or approximately 3,440,424 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 5,340.535 | 13,831.922 | 3,417,942.4 |
| Water | 35.127 | 90.979 | 22,481.3 |
| Total | 5,375.662 | 13,922.901 | 3,440,423.7 |
How Natrona County compares
By original Census land area, Natrona County ranks #5 of 23 in Wyoming and #71 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.336 times the Wyoming county-equivalent median of 3,996.8 square miles. It accounts for 5.5% of the combined county land area in the state.
See the complete Wyoming ranking · What counts as a county equivalent?
Population and density of Natrona County
The Census Bureau estimates that 80,526 people lived in Natrona County on July 1, 2025. That ranks #736 of 3,222 county equivalents nationally and #2 of 23 in Wyoming. Since the April 1, 2020 estimates base of 79,965, the population has grown by 561 (+0.7%), compared with +2.1% for Wyoming as a whole.
With 5,340.5 square miles of land, that is 15 people per square mile (5.8 per km²), placing Natrona County #2,473 nationally for density and #2 in Wyoming. The median county equivalent has 47 people per square mile; the Wyoming median is 4.1. Put another way, there are about 42 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 80,299 | 79,665 | 79,585 | 79,976 | 80,271 | 80,526 |
| Change | — | −634 | −80 | +391 | +295 | +255 |
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 Natrona County
6 incorporated places lie at least partly in Natrona County. Together they are home to 69,742 people (86.6%); the other 10,784 (13.4%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Casper city, with 58,771 residents in the county. Among places with at least 1,000 residents in 2020, Mills town grew fastest since then (+10.4%).
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Casper cityCounty seat | 58,771 | −0.6% | 26.6 |
| Mills town | 4,634 | +10.4% | 5.03 |
| Bar Nunn town | 3,012 | +1.1% | 2.113 |
| Evansville town | 2,875 | +3.9% | 3.921 |
| Midwest town | 292 | +2.1% | 0.432 |
| Edgerton town | 158 | +3.3% | 0.255 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Natrona County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Natrona County is a central county of the Casper, WY Metropolitan Statistical Area. Natrona County is the area’s only county equivalent, so the metro area has the same 5,340.5 square miles of land. By combined land it ranks #45 of 393 metropolitan areas, and #384 by population.
ZIP codes
14 ZIP Code Tabulation Areas have land in Natrona County; 12 of them have most of their land inside the county, and the others mainly cover neighboring areas.
8260182604826098262082630826358263682638826398264282643826448264682648
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 Natrona County
Natrona County shares a land border with 5 county equivalents. It has more land than 3 of them. The largest neighbor is Fremont County (9,183.6 mi²) and the smallest is Washakie County (2,238.7 mi²). Together with its neighbors, Natrona County forms a block of 33,069.7 mi² of land, of which it holds 16.1%.
| Bordering county equivalent | Land mi² | Size vs. Natrona | Compare |
|---|---|---|---|
| Fremont County | 9,183.6 | 1.7× larger | Compare |
| Carbon County | 7,897.7 | 1.5× larger | Compare |
| Converse County | 4,255 | 1.3× smaller | Compare |
| Johnson County | 4,154.2 | 1.3× smaller | Compare |
| Washakie County | 2,238.7 | 2.4× smaller | Compare |
How big is Natrona County compared with U.S. states?
Natrona County has more land than 3 of the 50 states. It is about 1.1 times the land area of Connecticut (4,842.5 mi²), while Hawaii, the next larger state, has 1.2 times as much land (6,422.6 mi²). Wyoming’s county land could hold about 18 areas the size of Natrona County.
Another way to picture it: the same land area would fill a square about 73.1 miles (117.6 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 Natrona County?
Natrona County has more land than 3,151 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 Natrona County at #74 nationally by total area, 3 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 0.7%, compared with a national county-equivalent median of 1.2% — 0.5 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 Natrona County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #70 | Pinal County, Arizona | 5,366.7 | Compare |
| #71 | Natrona County, Wyoming | 5,340.5 | This county |
| #72 | Prince of Wales-Hyder Census Area, Alaska | 5,268.2 | 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 42.981299, -106.770652. 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: 13,831,920,272 m²; AWATER: 90,977,263 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 big is Natrona County?
Natrona County, Wyoming has 5,340.5 square miles (13,831.9 km²) of land and 35.1 square miles of water, for a total area of 5,375.7 square miles. It ranks #71 of 3,222 U.S. county equivalents by land area.
Is Natrona County the largest county in Wyoming?
No. Natrona County ranks #5 of 23 in Wyoming by land area. The largest is Sweetwater County, with 10,427 square miles of land.
What counties border Natrona County?
Natrona County shares a land border with Fremont County, Converse County, Carbon County, Johnson County, and Washakie County.
What is the population of Natrona County?
The Census Bureau estimates Natrona County had 80,526 residents on July 1, 2025, ranking #736 of 3,222 county equivalents. That is 15 people per square mile of land.
What is the county seat of Natrona County?
The county seat of Natrona County is Casper.
What cities and towns are in Natrona County?
Natrona County has 6 incorporated places. The most populous five are Casper city, Mills town, Bar Nunn town, Evansville town, and Midwest town; 10,784 residents live outside any incorporated place.
Is Natrona County part of a metropolitan area?
Yes. It is a central county of the Casper, WY Metropolitan Statistical Area.
How many ZIP codes are in Natrona County?
14 ZIP Code Tabulation Areas have land in Natrona County, and 12 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Natrona County compare with U.S. states?
It has more land than 3 of the 50 states, including Connecticut (4,842.5 square miles of land).
How many acres of land are in Natrona County?
The land measurement converts to approximately 3,417,942 acres. Including water, total area is approximately 3,440,424 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.