Wyoming State Highways
For each route signed as an Interstate, U.S., or State Highway, Wyoming DOT has an inventory control route number. This control number determines the mileposts on all state-maintained highways. The system changed between 1997 and 2012. Under the older system, the state control route number typically had an alphabetical prefix followed by a number. For example, Interstate highways were inventoried with the prefix “I” followed by the signed route number. Therefore, Interstate 80 is inventory control route I-80. For U.S. and state routes, the state has identified its own set of hidden numbers that usually do not match the signed route number. For example, U.S. 287 carries eight separate inventory control route numbers (P-23, S-410, I-80, P-21, P-20, P-15, P-30, and P-10) on its diagonal course across the state. “P” typically meant primary, “U” meant urban, and “S” meant secondary. In some cases, the route carried its own designation. For example, WYO 344 was known as inventory control route SH-344. But in most cases, secondary and primary routes had inventory control numbers that varied from the signed route number.
By 2012, this system had changed and no longer uses the alphabetical prefix system described above and are instead assigned a number up to four digits that may or may not correspond to the signed route number. Generally, the control number does not match the signed route number. This system makes some degree of sense given the high number of roads that have more than one assigned route number (for example, U.S. 20 overlaps with U.S. 14, U.S. 16, WYO 789, U.S. 26, Interstate 25, U.S. 87, and U.S. 18 on its route east across Wyoming). To see the current description of routes and highways in Wyoming, review the official 2017 Maintenance Section Reference Book.
Pages on this site were originally compiled with the 1997 route numbering. Subsequent updates use more recent data.
Wyoming’s mileposts are based on the inventory number described above, so the mileposts along a given route may not be unique only to that signed route number. A route such as U.S. 287 utilizes several control routes across the state.
If WyoDOT realigns a highway or joins two highways under one state control number, an BACK=AHEAD (BK=AH) equation is typically used to keep the mileposts in sync. For example, 1.01BK=34.76AH means that the 1.01 milepost equals the 34.76 milepost. This means that the distance between Milepost 1.00 and Milepost 35.00 is only 0.25 mile. Milepost equations remain in use under the new route inventorying system.
Wyoming Highways in the National Highway System
- Interstate 25 – Colorado State Line to Buffalo
- Interstate 80 – Utah State Line to Nebraska State Line
- Interstate 90 – Montana State Line to South Dakota State Line
- Interstate 180 – Cheyenne/Central Avenue Spur
- U.S. 14 – Yellowstone to Sheridan
- Alternate U.S. 14 – Cody to Lovell
- U.S. 16 – Gillette to Rapid City
- U.S. 18 – Orin to Lusk; Lusk to Mule Creek Junction; Mule Creek Junction to Hot Springs, South Dakota, and South Dakota 79 junction). The route from Orin to Rapid City via U.S. 18 and South Dakota 79 is a STRANET Route.
- U.S. 20 – Greybull to Shoshoni; Shoshoni to Casper; Lusk to Chadron, Nebraska
- U.S. 26 – Diversion Dam to Riverton; Riverton to Shoshoni; Dwyer to Ogallala, Nebraska
- U.S. 30 – Cokeville to Granger
- U.S. 85 – Cheyenne to Deadwood, South Dakota
- U.S. 89 – Ogden, Utah, to Moran Junction
- WYO 89 – Cokeville to Geneva, Idaho
- WYO 114 – Lovell to Deaver
- U.S. 212 – through Colony, between Crow Agency, Montana, and Belle Fourche, South Dakota
- WYO 220 – Muddy Gap to Casper
- U.S. 287 – Fort Collins, Colorado, to Laramie; Rawlins to Muddy Gap; Muddy Gap to Lander; Lander to Diversion Dam; Diversion Dam to Moran Junction
- U.S. 310 – Greybull to Laurel, Montana, via Frannie
- WYO 789 – Lander to Riverton
In addition, the following routes were submitted for inclusion in Wyoming’s National Highway System in 1995, but they were not adopted:
Wyoming License Plates
License plates in the state of Wyoming feature the “bucking horse and rider.” This horse has appeared on Wyoming license plates since 1936. The number to the left of the bronco is a code to determine the vehicle’s county of origin, while the number to the right of the bronco is the vehicle’s identifying number. That number is usually a combination of four numbers or three numbers plus a two-digit letter code. Later versions of the plate have three numbers and a letter or combination of letters. Vanity plates are the county number and a one, two, three, or four-letter word — of course, some four-letter words are not allowed! Plates are currently silkscreened, but until 2003 they were embossed.
This list shows the county numbers and the county represented by that number. The number represents the ranking of the county according to their total county property valuation. If the counties were re-evaluated today, this order would no longer be true. Note that the clustering of Wyoming state routes is ordered alphabetically, not in the license plate order. Thus, Albany County has State Routes 10-29, but it is County #5 on license plates.