County outline
Where Clay County is located
Area breakdown
Land accounts for 91.2% of Clay County’s measured area and water for 8.8%. Its combined area converts to 671.7 square kilometers or approximately 165,980 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 236.529 | 612.607 | 151,378.6 |
| Water | 22.814 | 59.088 | 14,601 |
| Total | 259.343 | 671.695 | 165,979.5 |
How Clay County compares
By original Census land area, Clay County ranks #84 of 95 in Tennessee and #2936 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.542 times the Tennessee county-equivalent median of 436.1 square miles. It accounts for 0.6% of the combined county land area in the state.
See the complete Tennessee ranking · What counts as a county equivalent?
Population and density of Clay County
The Census Bureau estimates that 7,821 people lived in Clay County on July 1, 2025. That ranks #2,663 of 3,222 county equivalents nationally and #90 of 95 in Tennessee. Since the April 1, 2020 estimates base of 7,579, the population has grown by 242 (+3.2%), compared with +5.8% for Tennessee as a whole.
With 236.5 square miles of land, that is 33 people per square mile (13 per km²), placing Clay County #1,918 nationally for density and #88 in Tennessee. The median county equivalent has 47 people per square mile; the Tennessee median is 76. Put another way, there are about 19 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 7,588 | 7,586 | 7,621 | 7,666 | 7,810 | 7,821 |
| Change | — | −2 | +35 | +45 | +144 | +11 |
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 Clay County
1 incorporated place lies at least partly in Clay County. Together they are home to 1,412 people (18.1%); the other 6,409 (81.9%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Celina city, with 1,412 residents in the county.
Metropolitan area
Clay 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
7 ZIP Code Tabulation Areas have land in Clay County; 2 of them have most of their land inside the county, and the others mainly cover neighboring areas.
37150385413855138568385733857538588
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 Clay County
Clay County shares a land border with 7 county equivalents, including 3 in Kentucky. It has more land than 2 of them. The largest neighbor is Overton County (433.5 mi²) and the smallest is Pickett County (163 mi²). Together with its neighbors, Clay County forms a block of 2,280.6 mi² of land, of which it holds 10.4%.
| Bordering county equivalent | Land mi² | Size vs. Clay | Compare |
|---|---|---|---|
| Overton County | 433.5 | 1.8× larger | Compare |
| Monroe CountyKentucky | 329.5 | 1.4× larger | Compare |
| Jackson County | 308.8 | 1.3× larger | Compare |
| Macon County | 307.1 | 1.3× larger | Compare |
| Cumberland CountyKentucky | 305.1 | 1.3× larger | Compare |
| Clinton CountyKentucky | 197.1 | 1.2× smaller | Compare |
| Pickett County | 163 | 1.5× smaller | Compare |
How big is Clay County compared with U.S. states?
Clay County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 4.4 times as much. Tennessee’s county land could hold about 174 areas the size of Clay County.
Another way to picture it: the same land area would fill a square about 15.4 miles (24.8 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 Clay County?
Clay County has more land than 286 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 Clay County at #2,927 nationally by total area, 9 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 8.8%, compared with a national county-equivalent median of 1.2% — 7.6 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 Clay County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2935 | Massac County, Illinois | 237.2 | Compare |
| #2936 | Clay County, Tennessee | 236.5 | This county |
| #2937 | Alexander County, Illinois | 235.4 | 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 36.545749, -85.545717. 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: 612,608,165 m²; AWATER: 59,089,265 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 Clay County?
Clay County, Tennessee has 236.5 square miles (612.6 km²) of land and 22.8 square miles of water, for a total area of 259.3 square miles. It ranks #2936 of 3,222 U.S. county equivalents by land area.
Is Clay County the largest county in Tennessee?
No. Clay County ranks #84 of 95 in Tennessee by land area. The largest is Shelby County, with 752.8 square miles of land.
What counties border Clay County?
Clay County shares a land border with Jackson County, Monroe County, Kentucky, Overton County, Macon County, Cumberland County, Kentucky, Pickett County, and Clinton County, Kentucky.
What is the population of Clay County?
The Census Bureau estimates Clay County had 7,821 residents on July 1, 2025, ranking #2,663 of 3,222 county equivalents. That is 33 people per square mile of land.
What is the county seat of Clay County?
The county seat of Clay County is Celina.
Is Clay County part of a metropolitan area?
No. Clay County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.
How many ZIP codes are in Clay County?
7 ZIP Code Tabulation Areas have land in Clay 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 Clay County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 4.4 times as much land.
How many acres of land are in Clay County?
The land measurement converts to approximately 151,379 acres. Including water, total area is approximately 165,980 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.