| County |
Two-Digit Code |
Three-Digit Code |
| Adams |
TE-UF, GA-GG |
SAA-TZZ |
| Alamosa |
XE-XG |
EAA-EBD |
| Arapahoe |
PH-RP, FA-FG |
PAA-RZZ |
| Archuleta |
YU |
FAA-FAL |
| Baca |
WG |
EBE-EBW |
| Bent |
XC |
EBX-ECL |
| Boulder |
ML-NF, FH-FP |
MAA-NZZ |
| Chaffee |
XH-XK |
FAM-FCC |
| Cheyenne |
YR |
ECM-ECT |
| Clear Creek |
YY-YZ |
ECU-EDU |
| Conejos |
WS |
EDV-EEK |
| Costilla |
YA |
EEL-EES |
| Crowley |
XW-XX |
EET-EFA |
| Custer |
ZA |
EFB-EFG |
| Delta |
VL-VN |
|
| Denver |
AA-CV |
AAA-DZZ |
| Dolores |
ZH |
EHR-EHV |
| Douglas |
YS-YT |
EHW-EMA |
| Eagle |
YM-YN |
EMB-EPA |
| El Paso |
JX-LL, FR-FT, FV |
KAA-LZZ |
| Elbert |
XS-XT |
EPB-EPU |
| Fremont |
UP-UT |
EPV-ETV |
| Garfield |
WM-WR |
ETM-ETW |
| Gilpin |
ZK |
EWN-EWV |
| Grand |
ZB-ZC |
EWZ-EYB |
| Gunnison |
YD-YE |
EYC-EZC |
| Hinsdale |
ZN |
EZD-EZE |
| Huerfano |
VE |
EZF-EZW |
| Jackson |
ZJ |
FGC-FGH |
| Jefferson |
RS-TD, HG-HW |
GAA-JZZ |
| Kiowa |
YP |
WUS-WUY |
| Kit Carson |
WU-WV |
WUZ-WVV |
|
|
| County |
Two-Digit Code |
Three-Digit Code |
| La Plata |
VV-VY |
FDF-FGB |
| Lake |
YF-YH |
FCD-FDE |
| Larimer |
LU-MK, FX-FY |
FHA-FZZ |
| Las Animas |
LM-LN |
UAA-UBK |
| Lincoln |
XP-XR |
UBL-UCA |
| Logan |
UG-UJ |
UCB-UEH |
| Mesa |
NG-NT |
UEJ-UNL |
| Mineral |
ZM |
UNM-UNR |
| Moffat |
YJ-YK |
UNS-UPX |
| Montezuma |
XL-XN |
UPY-USL |
| Montrose |
WB-WD |
USM-UUZ |
| Morgan |
UW-UY |
UVA-UXR |
| Otero |
PA-PC |
UXS-UZZ |
| Ouray |
ZF |
VAA-VAG |
| Park |
ZD |
VAH-VBA |
| Phillips |
XY-XZ |
VBB-VBR |
| Pitkin |
ZG-ZP |
VBS-VDM |
| Prowers |
VG-VH |
VDN-VEY |
| Pueblo |
GP-HD |
VEC-VVC |
| Rio Blanco |
YV-YW |
VVD-VVV |
| Rio Grande |
WJ-WL |
VVW-VWZ |
| Routt |
WZ-XA |
VXA-VYN |
| Saguache |
XU-XV |
VYP-VZA |
| San Juan |
ZE |
VZB-VZE |
| San Miguel |
YX |
VZF-VZR |
| Sedgwick |
YB-YC |
WNL-WNY |
| Summit |
ZL, ZR |
WNZ-WRM |
| Teller |
YL |
WRN-WSR |
| Washington |
WW |
WST-WTK |
| Weld |
HY-JM |
WAA-WNK |
| Yuma |
VS-VT |
WTL-WUR |
| Rental Car/Overflow |
n/a |
ZAA-ZZZ |
|