County ZIP codes · Louisiana · FIPS 22101
St. Mary Parish, LA ZIP Codes
St. Mary Parish, Louisiana has 11 ZIP codes (Census 2020 ZCTA-county file; GeoNames postal codes, October 2026): 9 residential and 2 for PO boxes or a single organization. 7 of the residential ones lie mainly in St. Mary Parish and 2 mainly in a neighboring county; 2 cross the county line. Median household income ranges from $52,407 in 70538 (Franklin) to $57,959 in 70392 (Patterson) (Census Bureau, ACS 2020-2024).
- ACS2020-24
- Census2020
Where are the ZIP codes of St. Mary Parish?
Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries; ACS 2020-2024 5-year estimates (B19013).
How different are its ZIP codes?
The middle half of its ranked ZIP codes (1,000+ people living in households) report median household incomes between $52,407 and $54,601.
They carry 9 postal town names.
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B19013).
All 9 residential ZIP codes in St. Mary Parish
7 ZIP codes lie mainly in St. Mary Parish; 2 more reach into it from a neighboring county and follow the first table.
| In this county | ||||||
|---|---|---|---|---|---|---|
| 70538 | Franklin | 12,464 | 54 | $52k | $118k | 100% |
| 70392 | Patterson | 8,173 | 222 | $58k | $159k | 100% |
| 70342 | Berwick | 4,607 | 617 | $52k | $212k | 100% |
| 70514 | Baldwin | 1,914 | 415 | $32k | $116k | 100% |
| 70522 | Centerville | 495 | 634 | $26k | – | 100% |
| 70523 | Charenton | 476 | 345 | $63k | $120k | 100% |
| 70340 | Amelia | no residents | 0 | – | – | 100% |
Partly in St. Mary Parish
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates; county shares by land area (Census 2020 ZCTA-county relationship file).
Which ZIP codes cross the county line?
2 ZIP codes of St. Mary Parish extend into another county. A ZIP code follows mail routes, not county borders.
| ZIP | In St. Mary | Elsewhere |
|---|---|---|
| 70380 | 32% | Assumption Parish 39%; St. Martin Parish 29% |
| 70544 | 47% | Iberia Parish 53% |
Source: U.S. Census Bureau, 2020 ZCTA-county relationship file (shares of land area).
PO Box and single-organization ZIP codes
| ZIP | Postal name |
|---|---|
| 70381 | Morgan City |
| 70540 | Garden City |
Source: GeoNames postal codes (CC BY 4.0).
Which first three digits do St. Mary Parish's ZIP codes use?
The first three digits of a ZIP code name the sectional center, the mail processing plant that sorts it. St. Mary Parish's ZIP codes use 2 prefixes: 703 and 705.
Source: U.S. Postal Service, labeling list L005 (3-digit ZIP Code prefix groups, SCF sortation), effective October 1, 2026.