ZIP Code 20191 — Reston, VA
20191 is a standard (street delivery) ZIP code serving Reston, Virginia, in Fairfax 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 20191 at a glance
| ZIP code | 20191 |
|---|---|
| Primary city | Reston |
| State | Virginia (VA) |
| County | Fairfax FIPS 51059 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 31,011 |
| Coordinates | 38.934380, -77.351840 |
How ZIP+4 works in 20191
The four digits after the hyphen encode a delivery segment inside 20191. 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 20191 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 Reston
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 20191.
| ZIP | City | Distance |
|---|---|---|
| 20190 | Reston, VA | 1.9 mi |
| 20171 | Herndon, VA | 2.6 mi |
| 22124 | Oakton, VA | 3.2 mi |
| 20194 | Reston, VA | 3.2 mi |
| 20170 | Herndon, VA | 3.5 mi |
| 22181 | Vienna, VA | 3.7 mi |
| 22182 | Vienna, VA | 4.2 mi |
| 22033 | Fairfax, VA | 4.4 mi |
| 22035 | Fairfax, VA | 5.4 mi |
| 20151 | Chantilly, VA | 5.6 mi |
| 22066 | Great Falls, VA | 5.9 mi |
| 22180 | Vienna, VA | 5.9 mi |
Questions about 20191
What is the ZIP+4 code for 20191?
20191 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 20191, you need to look up a specific street address to get them.
What city is 20191?
20191 is assigned to Reston, Virginia, in Fairfax 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.