County outline
Where Oneida County is located
Area breakdown
Land accounts for 99.9% of Oneida County’s measured area and water for 0.1%. Its combined area converts to 3,109.3 square kilometers or approximately 768,316 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 1,198.952 | 3,105.271 | 767,329.3 |
| Water | 1.542 | 3.994 | 986.9 |
| Total | 1,200.494 | 3,109.265 | 768,316.2 |
How Oneida County compares
By original Census land area, Oneida County ranks #26 of 44 in Idaho and #511 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.911 times the Idaho county-equivalent median of 1,315.7 square miles. It accounts for 1.5% of the combined county land area in the state.
See the complete Idaho ranking · What counts as a county equivalent?
Population and density of Oneida County
The Census Bureau estimates that 5,085 people lived in Oneida County on July 1, 2025. That ranks #2,888 of 3,222 county equivalents nationally and #38 of 44 in Idaho. Since the April 1, 2020 estimates base of 4,565, the population has grown by 520 (+11.4%), compared with +10.4% for Idaho as a whole.
With 1,199 square miles of land, that is 4.2 people per square mile (1.6 per km²), placing Oneida County #2,884 nationally for density and #33 in Idaho. The median county equivalent has 47 people per square mile; the Idaho median is 10. Put another way, there are about 151 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 4,564 | 4,604 | 4,740 | 4,968 | 5,016 | 5,085 |
| Change | — | +40 | +136 | +228 | +48 | +69 |
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 Oneida County
1 incorporated place lies at least partly in Oneida County. Together they are home to 2,338 people (46%); the other 2,747 (54%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Malad City city, with 2,338 residents in the county.
Metropolitan area
Oneida County is an outlying county of the Brigham City, UT-ID Micropolitan Statistical Area. Its 2 county equivalents have 70,405 residents on 6,980.3 square miles of land; Oneida County accounts for 17.2% of the land and 7.2% of the residents. By combined land it ranks #10 of 542 micropolitan areas, and #108 by population. It belongs to the Salt Lake City-Provo-Orem, UT-ID Combined Statistical Area.
| County equivalent | Population 2025 | Land mi² |
|---|---|---|
| Box Elder CountyUtah | 65,320 | 5,781.3 |
| Oneida County | 5,085 | 1,199 |
ZIP codes
4 ZIP Code Tabulation Areas have land in Oneida County; 2 of them have most of their land inside the county, and the others mainly cover neighboring areas.
83212832438325283342
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 Oneida County
Oneida County shares a land border with 6 county equivalents, including 2 in Utah. It has more land than 3 of them. The largest neighbor is Box Elder County (5,781.3 mi²) and the smallest is Franklin County (663.1 mi²). Together with its neighbors, Oneida County forms a block of 13,889.9 mi² of land, of which it holds 8.6%.
| Bordering county equivalent | Land mi² | Size vs. Oneida | Compare |
|---|---|---|---|
| Box Elder CountyUtah | 5,781.3 | 4.8× larger | Compare |
| Cassia County | 2,565.6 | 2.1× larger | Compare |
| Power County | 1,403.8 | 1.2× larger | Compare |
| Cache CountyUtah | 1,164.7 | about the same | Compare |
| Bannock County | 1,112.5 | 1.1× smaller | Compare |
| Franklin County | 663.1 | 1.8× smaller | Compare |
How big is Oneida County compared with U.S. states?
Oneida County has more land than 1 of the 50 states. It is about 1.2 times the land area of Rhode Island (1,033.9 mi²), while Delaware, the next larger state, has 1.6 times as much land (1,948.6 mi²). Idaho’s county land could hold about 69 areas the size of Oneida County.
Another way to picture it: the same land area would fill a square about 34.6 miles (55.7 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 Oneida County?
Oneida County has more land than 2,711 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 Oneida County at #590 nationally by total area, 79 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 Oneida County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #510 | Lincoln County, Idaho | 1,201.4 | Compare |
| #511 | Oneida County, Idaho | 1,199 | This county |
| #512 | Dane County, Wisconsin | 1,196.5 | 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 42.183895, -112.520449. 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: 3,105,271,484 m²; AWATER: 3,993,019 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 Oneida County?
Oneida County, Idaho has 1,199 square miles (3,105.3 km²) of land and 1.542 square miles of water, for a total area of 1,200.5 square miles. It ranks #511 of 3,222 U.S. county equivalents by land area.
Is Oneida County the largest county in Idaho?
No. Oneida County ranks #26 of 44 in Idaho by land area. The largest is Idaho County, with 8,477.5 square miles of land.
What counties border Oneida County?
Oneida County shares a land border with Box Elder County, Utah, Power County, Bannock County, Cassia County, Franklin County, and Cache County, Utah.
What is the population of Oneida County?
The Census Bureau estimates Oneida County had 5,085 residents on July 1, 2025, ranking #2,888 of 3,222 county equivalents. That is 4.2 people per square mile of land.
What is the county seat of Oneida County?
The county seat of Oneida County is Malad City.
Is Oneida County part of a metropolitan area?
Yes. It is an outlying county of the Brigham City, UT-ID Micropolitan Statistical Area, which has 2 county equivalents and 70,405 residents.
How many ZIP codes are in Oneida County?
4 ZIP Code Tabulation Areas have land in Oneida County, and 2 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Oneida County compare with U.S. states?
It has more land than 1 of the 50 states, including Rhode Island (1,033.9 square miles of land).
How many acres of land are in Oneida County?
The land measurement converts to approximately 767,329 acres. Including water, total area is approximately 768,316 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.