ZIP Code 37031 — Castalian Springs, TN
37031 is a standard (street delivery) ZIP code serving Castalian Springs, Tennessee, in Sumner 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 37031 at a glance
| ZIP code | 37031 |
|---|---|
| Primary city | Castalian Springs |
| State | Tennessee (TN) |
| County | Sumner FIPS 47165 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Chicago |
| Population | 3,926 |
| Coordinates | 36.372100, -86.303280 |
How ZIP+4 works in 37031
The four digits after the hyphen encode a delivery segment inside 37031. 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 37031 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 37031.
| ZIP | City | Distance |
|---|---|---|
| 37087 | Lebanon, TN | 7 mi |
| 37066 | Gallatin, TN | 8.7 mi |
| 37022 | Bethpage, TN | 8.8 mi |
| 37074 | Hartsville, TN | 9.2 mi |
| 37151 | Riddleton, TN | 14.9 mi |
| 37186 | Westmoreland, TN | 15.4 mi |
| 37057 | Dixon Springs, TN | 15.5 mi |
| 37122 | Mount Juliet, TN | 16.9 mi |
| 37090 | Lebanon, TN | 17.1 mi |
| 37075 | Hendersonville, TN | 17.1 mi |
| 37148 | Portland, TN | 17.9 mi |
| 37048 | Cottontown, TN | 18 mi |
Questions about 37031
What is the ZIP+4 code for 37031?
37031 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 37031, you need to look up a specific street address to get them.
What city is 37031?
37031 is assigned to Castalian Springs, Tennessee, in Sumner 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.