County outline
Where St. Mary Parish is located
Area breakdown
Land accounts for 49.9% of St. Mary Parish’s measured area and water for 50.1%. Its combined area converts to 2,900.1 square kilometers or approximately 716,623 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 558.528 | 1,446.581 | 357,457.9 |
| Water | 561.195 | 1,453.488 | 359,164.8 |
| Total | 1,119.723 | 2,900.069 | 716,622.7 |
How St. Mary Parish compares
By original Census land area, St. Mary Parish ranks #43 of 64 in Louisiana and #1857 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.865 times the Louisiana county-equivalent median of 645.9 square miles. It accounts for 1.3% of the combined county land area in the state.
See the complete Louisiana ranking · What counts as a county equivalent?
What stands out about St. Mary Parish?
St. Mary Parish has more land than 1,365 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. Mary Parish at #653 nationally by total area, 1,204 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 50.1%, compared with a national county-equivalent median of 1.2% — 49 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. Mary Parish in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1856 | Blount County, Tennessee | 558.8 | Compare |
| #1857 | St. Mary Parish, Louisiana | 558.5 | This county |
| #1858 | Mahnomen County, Minnesota | 557.9 | 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 29.629349, -91.463804. 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: 1,446,581,792 m²; AWATER: 1,453,489,227 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 many acres of land are in St. Mary Parish?
The land measurement converts to approximately 357,458 acres. Including water, total area is approximately 716,623 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.