ZIP Code 40203 — Louisville, KY
40203 is a standard (street delivery) ZIP code serving Louisville, Kentucky, in Jefferson 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 40203 at a glance
| ZIP code | 40203 |
|---|---|
| Primary city | Louisville |
| State | Kentucky (KY) |
| County | Jefferson FIPS 21111 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Kentucky/Louisville |
| Population | 17,742 |
| Coordinates | 38.247220, -85.765000 |
How ZIP+4 works in 40203
The four digits after the hyphen encode a delivery segment inside 40203. 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 40203 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 Louisville
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 40203.
| ZIP | City | Distance |
|---|---|---|
| 40202 | Louisville, KY | 0.8 mi |
| 40210 | Louisville, KY | 1.6 mi |
| 40208 | Louisville, KY | 2 mi |
| 40204 | Louisville, KY | 2.5 mi |
| 40212 | Louisville, KY | 2.5 mi |
| 40217 | Louisville, KY | 2.6 mi |
| 40211 | Louisville, KY | 3.2 mi |
| 40206 | Louisville, KY | 3.5 mi |
| 40215 | Louisville, KY | 4.1 mi |
| 40280 | Louisville, KY | 4.2 mi |
| 40221 | Louisville, KY | 4.2 mi |
| 40209 | Louisville, KY | 4.5 mi |
Questions about 40203
What is the ZIP+4 code for 40203?
40203 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 40203, you need to look up a specific street address to get them.
What city is 40203?
40203 is assigned to Louisville, Kentucky, in Jefferson 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.