County outline
Where Massac County is located
Area breakdown
Land accounts for 98% of Massac County’s measured area and water for 2%. Its combined area converts to 627 square kilometers or approximately 154,936 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 237.152 | 614.221 | 151,777.3 |
| Water | 4.935 | 12.782 | 3,158.4 |
| Total | 242.087 | 627.002 | 154,935.7 |
How Massac County compares
By original Census land area, Massac County ranks #96 of 102 in Illinois and #2935 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.464 times the Illinois county-equivalent median of 510.7 square miles. It accounts for 0.4% of the combined county land area in the state.
See the complete Illinois ranking · What counts as a county equivalent?
Population and density of Massac County
The Census Bureau estimates that 13,502 people lived in Massac County on July 1, 2025. That ranks #2,260 of 3,222 county equivalents nationally and #76 of 102 in Illinois. Since the April 1, 2020 estimates base of 14,176, the population has declined by 674 (−4.8%), compared with −0.8% for Illinois as a whole.
With 237.2 square miles of land, that is 57 people per square mile (22 per km²), placing Massac County #1,435 nationally for density and #43 in Illinois. The median county equivalent has 47 people per square mile; the Illinois median is 44. Put another way, there are about 11 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 14,141 | 13,959 | 13,863 | 13,741 | 13,616 | 13,502 |
| Change | — | −182 | −96 | −122 | −125 | −114 |
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 Massac County
3 incorporated places lie at least partly in Massac County. Together they are home to 6,748 people (50%); the other 6,754 (50%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Metropolis city, with 5,727 residents in the county.
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Metropolis cityCounty seat | 5,727 | −3.9% | 6.008 |
| Brookport city | 691 | −4.7% | 0.653 |
| Joppa village | 330 | −5.4% | 0.486 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Massac County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Massac County is an outlying county of the Paducah, KY-IL Metropolitan Statistical Area. Its 5 county equivalents have 102,259 residents on 1,235.5 square miles of land; Massac County accounts for 19.2% of the land and 13.2% of the residents. By combined land it ranks #252 of 393 metropolitan areas, and #364 by population. It belongs to the Paducah-Mayfield, KY-IL Combined Statistical Area.
| County equivalent | Population 2025 | Land mi² |
|---|---|---|
| McCracken CountyKentucky | 67,553 | 248.8 |
| Massac County | 13,502 | 237.2 |
| Livingston CountyKentucky | 8,863 | 313 |
| Ballard CountyKentucky | 7,594 | 247.1 |
| Carlisle CountyKentucky | 4,747 | 189.5 |
ZIP codes
8 ZIP Code Tabulation Areas have land in Massac County; 5 of them have most of their land inside the county, and the others mainly cover neighboring areas.
6290862910629386294162943629536295662960
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 Massac County
Massac County shares a land border with 5 county equivalents, including 2 in Kentucky. It has more land than 1 of them. The largest neighbor is Pope County (368.9 mi²) and the smallest is Pulaski County (199.3 mi²). Together with its neighbors, Massac County forms a block of 1,710.8 mi² of land, of which it holds 13.9%.
| Bordering county equivalent | Land mi² | Size vs. Massac | Compare |
|---|---|---|---|
| Pope County | 368.9 | 1.6× larger | Compare |
| Johnson County | 343.7 | 1.4× larger | Compare |
| Livingston CountyKentucky | 313 | 1.3× larger | Compare |
| McCracken CountyKentucky | 248.8 | about the same | Compare |
| Pulaski County | 199.3 | 1.2× smaller | Compare |
How big is Massac County compared with U.S. states?
Massac 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. Illinois’s county land could hold about 234 areas the size of Massac 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 Massac County?
Massac County has more land than 287 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 Massac County at #2,966 nationally by total area, 31 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 2%, compared with a national county-equivalent median of 1.2% — 0.9 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 Massac County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2934 | Seminole County, Georgia | 237.6 | Compare |
| #2935 | Massac County, Illinois | 237.2 | This county |
| #2936 | Clay County, Tennessee | 236.5 | 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 37.216119, -88.705658. 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: 614,222,109 m²; AWATER: 12,780,833 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 Massac County?
Massac County, Illinois has 237.2 square miles (614.2 km²) of land and 4.935 square miles of water, for a total area of 242.1 square miles. It ranks #2935 of 3,222 U.S. county equivalents by land area.
Is Massac County the largest county in Illinois?
No. Massac County ranks #96 of 102 in Illinois by land area. The largest is McLean County, with 1,183.2 square miles of land.
What counties border Massac County?
Massac County shares a land border with Pope County, McCracken County, Kentucky, Johnson County, Pulaski County, and Livingston County, Kentucky.
What is the population of Massac County?
The Census Bureau estimates Massac County had 13,502 residents on July 1, 2025, ranking #2,260 of 3,222 county equivalents. That is 57 people per square mile of land.
What is the county seat of Massac County?
The county seat of Massac County is Metropolis.
What cities and towns are in Massac County?
Massac County has 3 incorporated places. The most populous are Metropolis city, Brookport city, and Joppa village; 6,754 residents live outside any incorporated place.
Is Massac County part of a metropolitan area?
Yes. It is an outlying county of the Paducah, KY-IL Metropolitan Statistical Area, which has 5 county equivalents and 102,259 residents.
How many ZIP codes are in Massac County?
8 ZIP Code Tabulation Areas have land in Massac County, and 5 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Massac 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 Massac County?
The land measurement converts to approximately 151,777 acres. Including water, total area is approximately 154,936 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.