County outline
Where Lyon County is located
Area breakdown
Land accounts for 83.3% of Lyon County’s measured area and water for 16.7%. Its combined area converts to 664.4 square kilometers or approximately 164,179 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 213.785 | 553.701 | 136,822.4 |
| Water | 42.744 | 110.706 | 27,356.2 |
| Total | 256.529 | 664.407 | 164,178.6 |
How Lyon County compares
By original Census land area, Lyon County ranks #95 of 120 in Kentucky and #2978 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.699 times the Kentucky county-equivalent median of 306 square miles. It accounts for 0.5% of the combined county land area in the state.
See the complete Kentucky ranking · What counts as a county equivalent?
Population and density of Lyon County
The Census Bureau estimates that 9,123 people lived in Lyon County on July 1, 2025. That ranks #2,552 of 3,222 county equivalents nationally and #101 of 120 in Kentucky. Since the April 1, 2020 estimates base of 8,678, the population has grown by 445 (+5.1%), compared with +2.2% for Kentucky as a whole.
With 213.8 square miles of land, that is 43 people per square mile (16 per km²), placing Lyon County #1,694 nationally for density and #79 in Kentucky. The median county equivalent has 47 people per square mile; the Kentucky median is 59. Put another way, there are about 15 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 8,673 | 8,426 | 9,100 | 9,177 | 9,077 | 9,123 |
| Change | — | −247 | +674 | +77 | −100 | +46 |
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 Lyon County
2 incorporated places lie at least partly in Lyon County. Together they are home to 2,969 people (32.5%); the other 6,154 (67.5%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Eddyville city, with 2,306 residents in the county.
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Eddyville cityCounty seat | 2,306 | −3.2% | 6.927 |
| Kuttawa city | 663 | +8% | 2.189 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Lyon County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Lyon County is not part of any metropolitan or micropolitan statistical area in the Office of Management and Budget’s July 2023 delineation; 1,306 other county equivalents are also outside one. These areas are built around an urban core of at least 10,000 people plus the counties tied to it by commuting, so counties outside them are generally rural.
ZIP codes
4 ZIP Code Tabulation Areas have land in Lyon County; 2 of them have most of their land inside the county, and the others mainly cover neighboring areas.
42038420554241142445
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 Lyon County
Lyon County shares a land border with 5 county equivalents. Each of them has more land than Lyon County. The largest neighbor is Trigg County (441.4 mi²) and the smallest is Marshall County (302.1 mi²). Together with its neighbors, Lyon County forms a block of 1,974.7 mi² of land, of which it holds 10.8%.
| Bordering county equivalent | Land mi² | Size vs. Lyon | Compare |
|---|---|---|---|
| Trigg County | 441.4 | 2.1× larger | Compare |
| Crittenden County | 359.6 | 1.7× larger | Compare |
| Caldwell County | 344.8 | 1.6× larger | Compare |
| Livingston County | 313 | 1.5× larger | Compare |
| Marshall County | 302.1 | 1.4× larger | Compare |
How big is Lyon County compared with U.S. states?
Lyon County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 4.8 times as much. Kentucky’s county land could hold about 185 areas the size of Lyon County.
Another way to picture it: the same land area would fill a square about 14.6 miles (23.5 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 Lyon County?
Lyon County has more land than 244 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 Lyon County at #2,934 nationally by total area, 44 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.
Its water share is 16.7%, compared with a national county-equivalent median of 1.2% — 15.5 percentage points higher. 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 Lyon County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2977 | St. John the Baptist Parish, Louisiana | 214.5 | Compare |
| #2978 | Lyon County, Kentucky | 213.8 | This county |
| #2979 | Calvert County, Maryland | 213.2 | 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 37.027771, -88.087914. 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: 553,700,580 m²; AWATER: 110,705,475 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 Lyon County?
Lyon County, Kentucky has 213.8 square miles (553.7 km²) of land and 42.7 square miles of water, for a total area of 256.5 square miles. It ranks #2978 of 3,222 U.S. county equivalents by land area.
Is Lyon County the largest county in Kentucky?
No. Lyon County ranks #95 of 120 in Kentucky by land area. The largest is Pike County, with 786.2 square miles of land.
What counties border Lyon County?
Lyon County shares a land border with Caldwell County, Trigg County, Livingston County, Marshall County, and Crittenden County.
What is the population of Lyon County?
The Census Bureau estimates Lyon County had 9,123 residents on July 1, 2025, ranking #2,552 of 3,222 county equivalents. That is 43 people per square mile of land.
What is the county seat of Lyon County?
The county seat of Lyon County is Eddyville.
What cities and towns are in Lyon County?
Lyon County has 2 incorporated places. The most populous are Eddyville city and Kuttawa city; 6,154 residents live outside any incorporated place.
Is Lyon County part of a metropolitan area?
No. Lyon County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.
How many ZIP codes are in Lyon County?
4 ZIP Code Tabulation Areas have land in Lyon 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 Lyon County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 4.8 times as much land.
How many acres of land are in Lyon County?
The land measurement converts to approximately 136,822 acres. Including water, total area is approximately 164,179 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.