| Code | Name | Region |
|---|---|---|
| USW56 | Wind Ridge | PA |
| USWID | Windber | PA |
| USWDR | Winder | GA |
| USWMY | Windermere | FL |
| USWF4 | Windfall | IN |
| USWMJ | Windham | CT |
| US6DW | Windham | ME |
| USWKH | Windham | NH |
| USWHM | Windham | OH |
| USDHM | Windham Hill | ME |
| USW7M | Windom | KS |
| USMWM | Windom | MN |
| USWOX | Windsor | CA |
| USWSR | Windsor | CO |
| USWND | Windsor | CT |
| USQCW | Wilton | CT |
| USIOV | Wilton | IA |
| USWYT | Wilton | ME |
| USWIO | Wilton | NH |
| USWIM | Wilton | NY |
| USWT8 | Wilton | WI |
| USWM8 | Wilton Manors | FL |
| USWIU | Wimauma | FL |
| USWJB | Wimberley | TX |
| USW9B | Wimbledon | ND |
| USWLZ | Winamac | IN |
| USYXW | Winburne | PA |
| USWCD | Winchendon | MA |
| USIHR | Winchester | CA |
| USIHS | Winchester | IL |
| USWCS | Winchester | IN |
| USWIN | Winchester | KY |
| USIHT | Winchester | MA |
| USWCH | Winchester | NH |
| USWFZ | Winchester | OH |
| USWOM | Wilmington | MA |
| USILM | Wilmington | NC |
| USIZG | Wilmington | NY |
| USILN | Wilmington | OH |
| USIMG | Wilmington | VA |
| USWMT | Wilmington | VT |
| USW6M | Wilmore | KY |
| USZFS | Wilmot | NH |
| USWT7 | Wilmot | WI |
| USWIQ | Wilson | AR |
| USWZO | Wilson | MI |
| USWSO | Wilson | NC |
| US8LS | Wilson | NY |
| USWQI | Wilson | TX |
| USIOF | Wilson | WI |