ZIP Code 63021 — Ballwin, MO
63021 is a standard (street delivery) ZIP code serving Ballwin, Missouri, in St. Louis 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 63021 at a glance
| ZIP code | 63021 |
|---|---|
| Primary city | Ballwin |
| State | Missouri (MO) |
| County | St. Louis FIPS 29189 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Chicago |
| Population | 55,666 |
| Coordinates | 38.568900, -90.545640 |
How ZIP+4 works in 63021
The four digits after the hyphen encode a delivery segment inside 63021. 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 63021 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 Ballwin
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 63021.
| ZIP | City | Distance |
|---|---|---|
| 63011 | Ballwin, MO | 2.5 mi |
| 63088 | Valley Park, MO | 2.8 mi |
| 63040 | Wildwood, MO | 4.8 mi |
| 63017 | Chesterfield, MO | 5.7 mi |
| 63049 | High Ridge, MO | 6.3 mi |
| 63131 | Saint Louis, MO | 6.4 mi |
| 63026 | Fenton, MO | 6.5 mi |
| 63025 | Eureka, MO | 6.7 mi |
| 63122 | Saint Louis, MO | 6.7 mi |
| 63038 | Wildwood, MO | 6.8 mi |
| 63127 | Saint Louis, MO | 7.5 mi |
| 63005 | Chesterfield, MO | 7.6 mi |
Questions about 63021
What is the ZIP+4 code for 63021?
63021 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 63021, you need to look up a specific street address to get them.
What city is 63021?
63021 is assigned to Ballwin, Missouri, in St. Louis 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.