Martin County area

Population and density of Martin County

The Census Bureau estimates that 166,272 people lived in Martin County on July 1, 2025. That ranks #427 of 3,222 county equivalents nationally and #33 of 67 in Florida. Since the April 1, 2020 estimates base of 158,432, the population has grown by 7,840 (+4.9%), compared with +8.9% for Florida as a whole.

With 543.9 square miles of land, that is 306 people per square mile (118 per km²), placing Martin County #503 nationally for density and #27 in Florida. The median county equivalent has 47 people per square mile; the Florida median is 209. Put another way, there are about 2.1 acres of land per resident.

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 Martin County

5 incorporated places lie at least partly in Martin County. Together they are home to 29,598 people (17.8%); the other 136,674 (82.2%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Stuart city, with 19,451 residents in the county. By land, Indiantown village is the largest at 14.5 mi². Among places with at least 1,000 residents in 2020, Stuart city grew fastest since then (+11.9%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Martin County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.

Metropolitan area

Martin County is a central county of the Port St. Lucie, FL Metropolitan Statistical Area. Its 2 county equivalents have 568,721 residents on 1,115.7 square miles of land; Martin County accounts for 48.7% of the land and 29.2% of the residents. By combined land it ranks #268 of 393 metropolitan areas, and #105 by population. It belongs to the Miami-Port St. Lucie-Fort Lauderdale, FL Combined Statistical Area.

ZIP codes

12 ZIP Code Tabulation Areas have land in Martin County; 9 of them have most of their land inside the county, and the others mainly cover neighboring areas.

334383345533458334693347834956349573497434990349943499634997

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 Martin County

Martin County shares a land border with 3 county equivalents. Each of them has more land than Martin County. The largest neighbor is Palm Beach County (1,964.3 mi²) and the smallest is St. Lucie County (571.9 mi²). Together with its neighbors, Martin County forms a block of 3,849.4 mi² of land, of which it holds 14.1%.

How big is Martin County compared with U.S. states?

Martin County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.9 times as much. Florida’s county land could hold about 99 areas the size of Martin County.

Another way to picture it: the same land area would fill a square about 23.3 miles (37.5 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 Martin County?

Martin County has more land than 1,304 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 Martin County at #1,277 nationally by total area, 641 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 27.8%, compared with a national county-equivalent median of 1.2% — 26.6 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 Martin County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

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.