County outline
Where Union County is located
Area breakdown
Land accounts for 99.9% of Union County’s measured area and water for 0.1%. Its combined area converts to 5,280.6 square kilometers or approximately 1,304,862 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 2,036.941 | 5,275.653 | 1,303,642.2 |
| Water | 1.906 | 4.937 | 1,219.8 |
| Total | 2,038.847 | 5,280.589 | 1,304,862.1 |
How Union County compares
By original Census land area, Union County ranks #16 of 36 in Oregon and #279 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.115 times the Oregon county-equivalent median of 1,826.2 square miles. It accounts for 2.1% of the combined county land area in the state.
See the complete Oregon ranking · What counts as a county equivalent?
Population and density of Union County
The Census Bureau estimates that 25,900 people lived in Union County on July 1, 2025. That ranks #1,635 of 3,222 county equivalents nationally and #24 of 36 in Oregon. Since the April 1, 2020 estimates base of 26,199, the population has declined by 299 (−1.1%), compared with +0.9% for Oregon as a whole.
With 2,036.9 square miles of land, that is 13 people per square mile (4.9 per km²), placing Union County #2,556 nationally for density and #23 in Oregon. The median county equivalent has 47 people per square mile; the Oregon median is 25. Put another way, there are about 50 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 26,171 | 26,288 | 26,157 | 25,934 | 25,945 | 25,900 |
| Change | — | +117 | −131 | −223 | +11 | −45 |
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 Union County
8 incorporated places lie at least partly in Union County. Together they are home to 19,405 people (74.9%); the other 6,495 (25.1%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is La Grande city, with 12,985 residents in the county.
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| La Grande cityCounty seat | 12,985 | −0.9% | 4.638 |
| Union city | 2,118 | −1.7% | 2.489 |
| Elgin city | 1,689 | −1.5% | 1.011 |
| Island City city | 1,142 | −1.5% | 0.984 |
| Cove city | 610 | −1.1% | 0.804 |
| North Powder city | 500 | −1% | 0.632 |
| Imbler city | 242 | −2% | 0.216 |
| Summerville town | 119 | 0% | 0.264 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Union County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Union County is a central county of the La Grande, OR Micropolitan Statistical Area. Union County is the area’s only county equivalent, so the micro area has the same 2,036.9 square miles of land. By combined land it ranks #78 of 542 micropolitan areas, and #473 by population.
ZIP codes
8 ZIP Code Tabulation Areas have land in Union County; 7 of them have most of their land inside the county, and the others mainly cover neighboring areas.
9781497824978279784197850978679787697883
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 Union County
Union County shares a land border with 4 county equivalents. Each of them has more land than Union County. The largest neighbor is Grant County (4,527.8 mi²) and the smallest is Baker County (3,068 mi²). Together with its neighbors, Union County forms a block of 15,994 mi² of land, of which it holds 12.7%.
| Bordering county equivalent | Land mi² | Size vs. Union | Compare |
|---|---|---|---|
| Grant County | 4,527.8 | 2.2× larger | Compare |
| Umatilla County | 3,215.5 | 1.6× larger | Compare |
| Wallowa County | 3,145.9 | 1.5× larger | Compare |
| Baker County | 3,068 | 1.5× larger | Compare |
How big is Union County compared with U.S. states?
Union County has more land than 2 of the 50 states. It is about 1 times the land area of Delaware (1,948.6 mi²), while Connecticut, the next larger state, has 2.4 times as much land (4,842.5 mi²). Oregon’s county land could hold about 47 areas the size of Union County.
Another way to picture it: the same land area would fill a square about 45.1 miles (72.6 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 Union County?
Union County has more land than 2,943 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 Union County at #314 nationally by total area, 35 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% — 1.1 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 Union County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #278 | Texas County, Oklahoma | 2,041.3 | Compare |
| #279 | Union County, Oregon | 2,036.9 | This county |
| #280 | Morrow County, Oregon | 2,030.5 | 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 45.304081, -117.999149. 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: 5,275,651,494 m²; AWATER: 4,936,781 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 Union County?
Union County, Oregon has 2,036.9 square miles (5,275.7 km²) of land and 1.906 square miles of water, for a total area of 2,038.8 square miles. It ranks #279 of 3,222 U.S. county equivalents by land area.
Is Union County the largest county in Oregon?
No. Union County ranks #16 of 36 in Oregon by land area. The largest is Harney County, with 10,134.5 square miles of land.
What counties border Union County?
Union County shares a land border with Umatilla County, Wallowa County, Baker County, and Grant County.
What is the population of Union County?
The Census Bureau estimates Union County had 25,900 residents on July 1, 2025, ranking #1,635 of 3,222 county equivalents. That is 13 people per square mile of land.
What is the county seat of Union County?
The county seat of Union County is La Grande.
What cities and towns are in Union County?
Union County has 8 incorporated places. The most populous five are La Grande city, Union city, Elgin city, Island City city, and Cove city; 6,495 residents live outside any incorporated place.
Is Union County part of a metropolitan area?
Yes. It is a central county of the La Grande, OR Micropolitan Statistical Area.
How many ZIP codes are in Union County?
8 ZIP Code Tabulation Areas have land in Union County, and 7 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Union County compare with U.S. states?
It has more land than 2 of the 50 states, including Delaware (1,948.6 square miles of land).
How many acres of land are in Union County?
The land measurement converts to approximately 1,303,642 acres. Including water, total area is approximately 1,304,862 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.