ZIP Code 48191 — Willis, MI
48191 is a standard (street delivery) ZIP code serving Willis, Michigan, in Washtenaw 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 48191 at a glance
| ZIP code | 48191 |
|---|---|
| Primary city | Willis |
| State | Michigan (MI) |
| County | Washtenaw FIPS 26161 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Detroit |
| Population | 4,403 |
| Coordinates | 42.120220, -83.564920 |
How ZIP+4 works in 48191
The four digits after the hyphen encode a delivery segment inside 48191. 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 48191 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 48191.
| ZIP | City | Distance |
|---|---|---|
| 48190 | Whittaker, MI | 2.1 mi |
| 48111 | Belleville, MI | 5.7 mi |
| 48197 | Ypsilanti, MI | 6.2 mi |
| 48160 | Milan, MI | 6.4 mi |
| 48159 | Maybee, MI | 6.5 mi |
| 48164 | New Boston, MI | 8.8 mi |
| 48117 | Carleton, MI | 9.3 mi |
| 48198 | Ypsilanti, MI | 10.8 mi |
| 48108 | Ann Arbor, MI | 11.1 mi |
| 48131 | Dundee, MI | 12 mi |
| 48188 | Canton, MI | 12.1 mi |
| 48174 | Romulus, MI | 12.4 mi |
Questions about 48191
What is the ZIP+4 code for 48191?
48191 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 48191, you need to look up a specific street address to get them.
What city is 48191?
48191 is assigned to Willis, Michigan, in Washtenaw 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.