St. Martin Parish area

Population and density of St. Martin Parish

The Census Bureau estimates that 51,106 people lived in St. Martin Parish on July 1, 2025. That ranks #1,014 of 3,222 county equivalents nationally and #20 of 64 in Louisiana. Since the April 1, 2020 estimates base of 51,750, the population has declined by 644 (−1.2%), compared with −0.9% for Louisiana as a whole.

With 737.5 square miles of land, that is 69 people per square mile (27 per km²), placing St. Martin Parish #1,267 nationally for density and #26 in Louisiana. The median county equivalent has 47 people per square mile; the Louisiana median is 48. Put another way, there are about 9.2 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 St. Martin Parish

7 incorporated places lie at least partly in St. Martin Parish. Together they are home to 15,389 people (30.1%); the other 35,717 (69.9%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Breaux Bridge city, with 7,652 residents in the county. The county seat, St. Martinville city, has 5,229 residents. By land, Broussard city is the largest at 18.2 mi² across all its counties. Among places with at least 1,000 residents in 2020, Breaux Bridge city grew fastest since then (+1.9%).

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

Metropolitan area

St. Martin Parish is an outlying county of the Lafayette, LA Metropolitan Statistical Area. Its 4 county equivalents have 423,758 residents on 2,833.7 square miles of land; St. Martin Parish accounts for 26% of the land and 12.1% of the residents. By combined land it ranks #104 of 393 metropolitan areas, and #133 by population. It belongs to the Lafayette-New Iberia-Opelousas, LA Combined Statistical Area.

ZIP codes

8 ZIP Code Tabulation Areas have land in St. Martin Parish; 3 of them have most of their land inside the county, and the others mainly cover neighboring areas.

7033970380705127051770518705197056070582

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 St. Martin Parish

St. Martin Parish shares a land border with 7 county equivalents. It has more land than 6 of them. The largest neighbor is St. Landry Parish (923.4 mi²) and the smallest is Lafayette Parish (268.8 mi²). Together with its neighbors, St. Martin Parish forms a block of 4,579.8 mi² of land, of which it holds 16.1%.

How big is St. Martin Parish compared with U.S. states?

St. Martin Parish has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.4 times as much. Louisiana’s county land could hold about 59 areas the size of St. Martin Parish.

Another way to picture it: the same land area would fill a square about 27.2 miles (43.7 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 St. Martin Parish?

St. Martin Parish has more land than 2,023 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 St. Martin Parish at #1,140 nationally by total area, 59 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 9.7%, compared with a national county-equivalent median of 1.2% — 8.5 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 St. Martin Parish 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.