ZIP Code 78588 — San Isidro, TX
78588 is a standard (street delivery) ZIP code serving San Isidro, Texas, in Starr County. To mail something here you only need these five digits — but the four-digit extension narrows delivery to a single point, and it is what USPS bulk postage discounts are priced on.
ZIP code 78588 at a glance
| ZIP code | 78588 |
|---|---|
| Primary city | San Isidro |
| State | Texas (TX) |
| County | Starr FIPS 48427 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Chicago |
| Population | 289 |
| Coordinates | 26.739660, -98.398520 |
How ZIP+4 works in 78588
The four digits after the hyphen encode a delivery segment inside 78588. In practice one segment usually means:
- One side of one block — odd numbers on a street between two cross streets
- A single large building, or one floor of it
- A group of PO boxes, sometimes a single box
- A single business that receives enough mail to warrant its own code
That is why 78588 has no single ZIP+4: two neighbors across the street from each other usually have different ones. Enter a street address above and we will return the exact nine-digit code along with the standardized USPS address format.
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 78588.
| ZIP | City | Distance |
|---|---|---|
| 78536 | Delmita, TX | 7.2 mi |
| 78591 | Santa Elena, TX | 10.3 mi |
| 78563 | Linn, TX | 10.4 mi |
| 78353 | Encino, TX | 14.1 mi |
| 78541 | Edinburg, TX | 21 mi |
| 78582 | Rio Grande City, TX | 25.2 mi |
| 78542 | Edinburg, TX | 27.8 mi |
| 78360 | Guerra, TX | 28 mi |
| 78540 | Edinburg, TX | 28.3 mi |
| 78576 | Penitas, TX | 28.9 mi |
| 78549 | Hargill, TX | 29 mi |
| 78574 | Mission, TX | 29.6 mi |
Questions about 78588
What is the ZIP+4 code for 78588?
78588 is the five-digit ZIP code. The ZIP+4 adds four more digits that identify a specific delivery point — usually one side of a city block, a single building, or a group of PO boxes. Because those four digits change from address to address within 78588, you need to look up a specific street address to get them.
What city is 78588?
78588 is assigned to San Isidro, Texas, in Starr County.
Do I need to use the ZIP+4?
It is optional for ordinary mail, but it speeds up sorting and it is required for most USPS bulk-mail postage discounts. Many address-verification and e-commerce systems also use ZIP+4 to confirm a delivery point exists.
Need thousands of these?
Upload a CSV and get ZIP+4, county, carrier route, and delivery-point data appended to every row — or call the API directly.