• parish
  • FIPS 22101
  • Largest town: Morgan City

St. Mary Parish, Louisiana

St. Mary Parish had 46,799 residents in the Census Vintage 2024 estimate, on 558.5 square miles of land. It ranks 23rd of 64 in Louisiana by population and 43rd by land area.

Population
46,799
#23 of 64 in Louisiana · #1,055 in US
Area
558.5 sq mi
#43 of 64 in Louisiana · #1,857 in US
Density
84 / sq mi
#24 of 64 in Louisiana · #1,042 in US
Median household income
$51,179
#39 of 64 in Louisiana · #2,634 in US

Census Vintage 2024 estimates · SAIPE 2023 income · 2024 Gazetteer land area

St. Mary Parish within Louisiana. Pin: Baton Rouge.

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Tools and pages that start from St. Mary Parish

St. Mary Parish population, land area and income

St. Mary Parish had 46,799 residents in the Census Vintage 2024 estimate, on 558.5 square miles of land. It ranks 23rd of 64 in Louisiana by population and 43rd by land area. That works out to 83.8 people per square mile, near the US average of 96.3, and above the national county median.

The median county-equivalent in Louisiana has 31,591 residents; St. Mary Parish is somewhat larger.

Its SAIPE 2023 median household income of $51,179 is in the bottom quarter among 3,143 counties with an estimate.

National rank among 3,144

Population

46,799

3144th1st

1055th of 3,144 (US)

Land area

559 sq mi

3144th1st

1857th of 3,144 (US)

Density

83.8 / sq mi

3144th1st

1042nd of 3,144 (US)

Median household income

$51,179

3143rd1st

2634th of 3,143 (US)

Rank within Louisiana (64)

Population

46,799

64th1st

23rd of 64 (LA)

Land area

559 sq mi

64th1st

43rd of 64 (LA)

Density

83.8 / sq mi

64th1st

24th of 64 (LA)

Median household income

$51,179

64th1st

39th of 64 (LA)

How St. Mary Parish's population changed since 2020

St. Mary Parish lost 2,356 residents between the July 2020 and July 2024 estimates, a drop of 4.8%. That ranks 51st of 64 in Louisiana for growth. The median Louisiana county changed by -2.3%, and the state as a whole by -1.2%.

Since the April 2020 estimates base, St. Mary Parish recorded 2,620 births and 2,967 deaths, a natural change of -347. Net international migration added +633 and net domestic migration, people moving to or from other US counties, came to -2,867. The largest single component was domestic migration, which removed 2,867 people.

49.2k202048.2k202147.8k202247.1k202346.8k2024
Census Vintage 2024 county estimates for July 1 of each year. The axis starts above zero so year-to-year changes are visible.

Components of change, April 2020 to July 2024

Births
2,620
Deaths
2,967
Net international migration
+633
Net domestic migration
-2,867
Change, July 2023 to July 2024
-332

Where St. Mary Parish is

The Census internal point of St. Mary Parish is at 29.629300, -91.463800. It sits in UTM zone 15N. The map shades Louisiana's 64 county-equivalents by population change from 2020 to 2024, darker for faster growth, with St. Mary Parish outlined. Dots are towns of 1,000+ people with residents in it.

Assumption Parish: -4.4%Concordia Parish: -4.2%Jackson Parish: -1.3%De Soto Parish: +1.6%Washington Parish: -0.6%Bienville Parish: -3.9%Caddo Parish: -5.1%Red River Parish: -4.6%Lafayette Parish: +5.0%Webster Parish: -4.6%Calcasieu Parish: -4.4%Allen Parish: -0.8%Rapides Parish: -2.9%Vernon Parish: -5.8%Union Parish: -2.3%St. Tammany Parish: +4.8%West Baton Rouge Parish: +4.3%Winn Parish: -2.3%Beauregard Parish: +0.2%Grant Parish: -0.2%Evangeline Parish: -1.7%Tangipahoa Parish: +4.6%St. Martin Parish: -0.8%Tensas Parish: -6.4%Caldwell Parish: -2.3%Franklin Parish: -3.1%Jefferson Parish: -2.8%Madison Parish: -8.3%Morehouse Parish: -6.6%Jefferson Davis Parish: -2.4%Pointe Coupee Parish: -4.0%Bossier Parish: +1.8%Richland Parish: -1.9%St. Charles Parish: -4.0%Acadia Parish: -1.5%Avoyelles Parish: -3.2%St. Mary Parish: -4.8%East Baton Rouge Parish: -0.6%Lafourche Parish: -2.2%Cameron Parish: -16.8%Terrebonne Parish: -5.1%LaSalle Parish: -0.9%Livingston Parish: +7.0%St. John the Baptist Parish: -6.3%Ouachita Parish: -1.4%Claiborne Parish: -4.0%St. Bernard Parish: +2.1%Orleans Parish: -5.4%St. Landry Parish: -1.8%Plaquemines Parish: -5.0%East Carroll Parish: -6.8%Vermilion Parish: +1.2%East Feliciana Parish: -1.7%Sabine Parish: -1.6%Iberia Parish: -3.6%Ascension Parish: +5.2%Lincoln Parish: -0.1%Natchitoches Parish: -3.8%St. James Parish: -5.0%St. Helena Parish: -0.4%Catahoula Parish: -6.4%West Carroll Parish: -4.5%West Feliciana Parish: -0.7%Iberville Parish: -1.0%
Change 2020 to 2024
  1. < -5.0%
  2. < -3.6%
  3. < -1.7%
  4. < -0.4%
  5. ≥ -0.4%
no data

Orange pin: St. Mary Parish internal point. Dark pin: Baton Rouge.

Internal point

Decimal
29.629300, -91.463800
DMS
29°37'45.48"N 91°27'49.68"W
UTM
15N 648719.7E 3278695.8N
Geohash
9vqbw9y54
Plus code
76XCJGHP+PF

Towns in St. Mary Parish

5 incorporated places of 1,000+ people have residents in St. Mary Parish, 28,871 people together, or 62% of the county. Each figure counts only the part of the town inside St. Mary Parish; towns marked "part" extend into another county. The largest is Morgan City with 10,813.

  1. 01Morgan City10,813
  2. 02Franklin6,284
  3. 03Patterson5,614
  4. 04Berwick4,495
  5. 05Baldwin1,665
Census Vintage 2024 subcounty estimates, county parts of incorporated places (SUMLEV 157).

Counties bordering St. Mary Parish

The Census 2024 county adjacency file lists 4 neighbors for St. Mary Parish. The most populous is Terrebonne Parish, LA, with 103,864 residents. Distances run between Census internal points in a straight line.

Distance to Baton Rouge and the nearest big city

Baton Rouge is 59.5 miles NNE of St. Mary Parish's internal point in a straight line. The nearest place of 100,000 or more is Lafayette, LA (population 122,280), 52.2 miles away. The nearest place of 10,000 or more is Morgan City, LA (population 10,813), 17.3 miles away.

St. Mary Parish FIPS code

The FIPS code of St. Mary Parish is 22101: state code 22 for Louisiana plus parish code 101. Use it as text, with the leading zero, when joining Census, BLS, or CDC county tables. SAIPE lists its 2023 median household income as $51,179.

Questions people ask

What is the population of St. Mary Parish, Louisiana?

The Census Vintage 2024 estimate for July 1, 2024 is 46,799. That is down 2,356 people (4.8%) from the July 2020 estimate of 49,155.

What is the FIPS code of St. Mary Parish?

22101. The first two digits (22) are Louisiana; the last three (101) identify the parish.

What is the largest town in St. Mary Parish?

Morgan City, with 10,813 residents inside St. Mary Parish in 2024.

Which counties border St. Mary Parish?

4 county-equivalents border it in the Census 2024 adjacency file: Terrebonne Parish, LA; Iberia Parish, LA; St. Martin Parish, LA; Assumption Parish, LA.

Sources and data as of

Data as of: Census Vintage 2024 population estimates, 2024 Gazetteer land area and internal points, SAIPE 2023 median household income.

  1. 01Census Vintage 2024 county population estimates
  2. 02Census 2024 Gazetteer, counties
  3. 03Census SAIPE 2023 state and county estimates
  4. 04Census Vintage 2024 subcounty population estimates
  5. 05Census 2024 county adjacency file
  6. 06Census 2024 cartographic boundary file, counties (1:5,000,000)

How every number is computed: methodology. Spotted a wrong figure? Report an error.