ZIP Code 91761 — Ontario, CA
91761 is a standard (street delivery) ZIP code serving Ontario, California, in San Bernardino 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 91761 at a glance
| ZIP code | 91761 |
|---|---|
| Primary city | Ontario |
| State | California (CA) |
| County | San Bernardino FIPS 06071 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Los_Angeles |
| Population | 62,935 |
| Coordinates | 34.035410, -117.591500 |
How ZIP+4 works in 91761
The four digits after the hyphen encode a delivery segment inside 91761. 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 91761 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.
Other ZIP codes in Ontario
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 91761.
| ZIP | City | Distance |
|---|---|---|
| 91764 | Ontario, CA | 2.8 mi |
| 91762 | Ontario, CA | 3 mi |
| 91752 | Mira Loma, CA | 4.3 mi |
| 91730 | Rancho Cucamonga, CA | 4.5 mi |
| 91710 | Chino, CA | 5.6 mi |
| 91786 | Upland, CA | 6.3 mi |
| 91708 | Chino, CA | 6.6 mi |
| 91763 | Montclair, CA | 6.6 mi |
| 92337 | Fontana, CA | 6.9 mi |
| 91701 | Rancho Cucamonga, CA | 7.1 mi |
| 92860 | Norco, CA | 7.9 mi |
| 92880 | Eastvale, CA | 8 mi |
Questions about 91761
What is the ZIP+4 code for 91761?
91761 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 91761, you need to look up a specific street address to get them.
What city is 91761?
91761 is assigned to Ontario, California, in San Bernardino 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.
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