ZIP Code 81123 — Blanca, CO
81123 is a standard (street delivery) ZIP code serving Blanca, Colorado, in Costilla 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 81123 at a glance
| ZIP code | 81123 |
|---|---|
| Primary city | Blanca |
| State | Colorado (CO) |
| County | Costilla FIPS 08023 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Denver |
| Population | 606 |
| Coordinates | 37.404690, -105.565900 |
How ZIP+4 works in 81123
The four digits after the hyphen encode a delivery segment inside 81123. 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 81123 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 81123.
| ZIP | City | Distance |
|---|---|---|
| 81133 | Fort Garland, CO | 13.4 mi |
| 81151 | Sanford, CO | 14.4 mi |
| 81101 | Alamosa, CO | 16.4 mi |
| 81146 | Mosca, CO | 17.8 mi |
| 81126 | Chama, CO | 20.6 mi |
| 81152 | San Luis, CO | 21.4 mi |
| 81141 | Manassa, CO | 24.6 mi |
| 81138 | Jaroso, CO | 26.5 mi |
| 81136 | Hooper, CO | 27.2 mi |
| 81055 | La Veta, CO | 27.8 mi |
| 81148 | Romeo, CO | 28.1 mi |
| 87524 | Costilla, NM | 30 mi |
Questions about 81123
What is the ZIP+4 code for 81123?
81123 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 81123, you need to look up a specific street address to get them.
What city is 81123?
81123 is assigned to Blanca, Colorado, in Costilla 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.