| Code | Name | Region |
|---|---|---|
| USB4R | Black Rock | AR |
| USAFG | Blackduck | MN |
| USBLK | Blackfoot | ID |
| USBK2 | Blackhawk | SD |
| USBL2 | Blackland, Rockwell | TX |
| USBZZ | Blacklick | OH |
| USBBH | Blacksburg | SC |
| USBCB | Blacksburg | VA |
| USXBG | Blackshear | GA |
| USBS2 | Blackshear, Pierce | GA |
| USVBK | Blackstock | SC |
| USA6H | Blackstone | MA |
| USBKT | Blackstone | VA |
| USJBI | Blackville | SC |
| US2BL | Blackwell | AR |
| USBWL | Blackwell | OK |
| USBQW | Blackwood | NJ |
| US8LY | Bladen | NE |
| USBIH | Bishop | CA |
| USYHP | Bishop | GA |
| USBHX | Bishop | TX |
| USB3V | Bishopville | MD |
| USBIV | Bishopville | SC |
| USB2S | Bismarck | AR |
| US2BS | Bismarck | IL |
| USBIS | Bismarck | ND |
| USN8S | Bison | KS |
| USIWX | Biwabik | MN |
| USBXY | Bixby | OK |
| USBC5 | Blachly | OR |
| USB97 | Black | MO |
| US6BY | Black Betsy | WV |
| USZA7 | Black Canyon City | AZ |
| USKAK | Black Creek | GA |
| USB4C | Black Creek | NC |
| USBLC | Black Creek | WI |
| USKDM | Black Diamond | WA |
| USHWJ | Black Hawk | CO |
| USBIR | Birchwood | AK |
| USB3W | Birchwood | TN |
| USIWO | Birchwood | WI |
| USXCG | Bird In Hand | PA |
| USIUB | Bird Island | MN |
| USBG6 | Birds Landing | CA |
| USBIB | Birdsboro | PA |
| USBHM | Birmingham | AL |
| USBIZ | Birmingham | MI |
| USBIN | Birmingham | NJ |
| USXY2 | Birmingham | OH |
| USIBJ | Birmingham | PA |