Wyoming Road Network

By | October 13, 2022

Interstate 80 west of Laramie in winter.

The road network is not very extensive. Most traffic is on Interstate Highways, Interstate 25, Interstate 80, and Interstate 90. In addition, there are also large areas that are not served by Interstates, especially in the northwest of the state. The roads are extremely quiet and consist almost entirely of through (freight) traffic. Traffic volumes are often very low, usually less than 20,000 vehicles, or even just 3,000 vehicles per day on the highways. The distances are long, in case of accidents medical assistance can take a long time due to the remoteness of some highway sections. Sometimes there are stretches of highway with 200 kilometers of no place with more than 1,000 inhabitants on the route.

Driving conditions are anything but ideal due to the harsh climate. Highways are regularly closed in the winter, especially the I-80 around Laramie is sensitive to this. In winter it is recommended to bring warm clothes, blankets and provisions. In addition, a jerry can with extra fuel is not an unnecessary luxury. The amounts of snow are usually moderate, but the wind can cause total white-out and the formation of snow dunes. Visibility on highways then often drops to less than one metre. In summer, trucks are not equally resistant to the strong wind gusts over the plains.

A standout in the Interstate network is Interstate 180 in Cheyenne, which is an ordinary city boulevard, signposted as I-180. In Wyoming there is a lot of double numbering, more than half of the US Highway network is double numbered with another road. Most routes are double numbered over 50% to 80% of their length, even quadruple numbered with other routes. This is especially the case in the wider area of ​​Yellowstone National Park, but also in other parts of the state. Due to the particularly low population density, multiple routes are unnecessary and double numbering is used.

Wyoming’s road network is very thin.

  • Bittranslators: State overview of Wyoming, including geography, economy, population and history as well as introduction to major cities of Wyoming.

Interstate Highways

I-80 forms the east-west route through the south of the state and serves as a throughput for traffic from the Midwest toward Salt Lake City and San Francisco. The highway also serves the state capital Cheyenne and other regional places such as Laramie, Rawlins, Rock Springs, Green River and Evanston. These places are usually not large, but they do have an important regional function. I-25 forms a north-south route leading from Denver, Colorado runs through Cheyenne and Casper to Buffalo and ends there on I-90. The portion of I-25 in Wyoming handles very little traffic due to its low population density and limited throughput. I-90 passes through northeastern Wyoming and is important for long-haul traffic from Seattle to Chicago. In Wyoming, the highway passes Sheridan, Buffalo and Gillette, all small towns.

  • Deluxesurveillance: Nickname of Wyoming as The Equality State. Also covers geography, history, economy, politics and administration of the state.


US 89 overlooking the Teton Range.

Wyoming was a state that did not have a single highway prior to the creation of the Interstate Highway system. The main route was US 30, which ran east-west through the south of the state. Parts of this route were a bit better developed, such as a multi-lane section between Laramie and Rawlins. Traveling took quite a bit of time on this route, although the average speed was still quite high because the larger towns were far apart and there was hardly any traffic. In the 1950s, only about 2,000 to 4,000 vehicles drove the US 30, mostly long-haul traffic. North-south traffic was conducted on US 85 and US 87 in the east of the state, but was somewhat less important because there are no major cities further north. US 14 and US 16 handled east-west traffic through the north of the state.

After the creation of the Interstate Highway system in 1956, highway construction in Wyoming began almost immediately. In 1958, the first freeway was opened, a stretch of I-25 in Cheyenne. During the 1960s, the network was largely constructed, except for a number of missing links. In particular, the bypasses of some larger towns, such as Gillette, Wheatland, Buffalo and Cheyenne, were built a little later, in the 1970s, partly because the various small towns on the routes of Interstate Highways were afraid of losing income, as they were partly dependent of through traffic.

After the early 1970s, some highway sections were still sparsely completed. Interstate 80 was the first to be completed, in 1977. I-25 and I-90 followed in 1982 and 1985. The last stretches to open were a portion of I-80 east of Cheyenne in 1977, a portion of I-25 south of Buffalo in 1982, and the portion of I-90 near the Montana border in 1985. Low highway construction costs, converted to dollars in 2010, approximately 2 to 3 million per kilometre. No new highways have opened in Wyoming since 1985. The population actually decreased slightly in the 1980s, and the growth has never been very impressive in absolute figures, as the state grew from 290,000 inhabitants in 1950 to 565,000 inhabitants in 2010.

US Highways

Many US Highways pass through Wyoming, especially to the north. There are many double numbers around Yellowstone National Park in the northwest of the state. No US Highways formally pass through Yellowstone National Park, although the roads are physically continuous, the US Highways do not extend beyond the boundaries of the park. This is the only national park in the United States where US Highways are formally interrupted.

US 20 has a through function from Yellowstone Park to Casper. US 26 runs from Casper to Jackson, the main town in northwestern Wyoming. In the far north, US 14 forms an east-west route, of little through importance east of Sheridan because of parallel I-90. A more important route is US 287, which runs from Yellowstone Park via Rawlins and Laramie to Fort Collins in Colorado. In terms of north-south routes, US 85 is a somewhat important connection from Cheyenne to Belle Fourche in South Dakota through eastern Wyoming. Other north-south routes are US 189 and US 191 to the west. US 30 and US 87 are almost completely double-numbered with Interstate Highways.

State Highways

The state highways often have a local importance and provide access to rural municipalities. The numbers are abbreviated to ‘WYO xxx’. wyo. is the former abbreviation for the state of Wyoming. The actual abbreviation is ‘WY’. Few state highways have a passing interest. In the northeast, WYO 59 is important for traffic from Cheyenne to Gillette because it is the shortest route. The WYO 220 handles some traffic from Rawlins to Casper and the WYO 28 handles traffic from Rock Springs to Casper and Buffalo through central Wyoming.


In 1916, the Federal Aid Road Act was passed by Congress. However, to qualify for federal funding, the state must have a Department of Highways or equivalent. That is why the Highway Department was established in 1917. Before that, the roads were a matter for the local authorities. Wyoming had more than 150,000 inhabitants at the time.

The road network of Wyoming at that time was still almost completely unpaved and hardly maintained, transport by road was extremely difficult. Another problem was that there was no organized snow removal until the 1920s. The Highway Department purchased its first snowplow in 1923. In 1929 33 snowplows were purchased, so that with nearly 50 snowplows, snow removal on a larger scale was possible. At that time, the important roads had been upgraded to gravel roads and the first asphalt roads had been created in the vicinity of larger towns.

In terms of the arrangement of the roads, there was initially talk of roads with a name. These names are still relatively well known today. Beginning in 1912, names were organized at the state level by the Wyoming Highways Association. In 1918 there were 16,000 cars in Wyoming, which increased to 62,000 by 1930. In 1922, the state of Wyoming decided to introduce road numbering. Road numbers were randomly assigned with no clear system. In 1926, the US Highway system was introduced, causing the state highways to quickly degenerate into secondary routes. Until the 1930s, the US Highways and state highways were still signposted double-numbered, after that no more. By the 1950s, nearly all of the original state highways had been renumbered.

The road network was upgraded from the end of the 1920s by applying oil surfacing on a large scale. This ensured that gravel roads were faster and more comfortable to drive, without the huge clouds of dust that characterized the state at the time. The first oil hardening was mainly applied around the capital Cheyenne in the southeast of the state. Nearly all major roads in Wyoming were paved between 1929 and 1939. This made the state much more accessible. From the 1940s onwards, the oil pavement was widely replaced by a permanent asphalt pavement, which lasted longer and required less maintenance. This pavement was more suitable for freight traffic.

Road numbering

The state highways in Wyoming have somewhat conspicuous road numbering. The numbering is based on the alphabetical order of the counties they pass through. For example, low numbers run in Albany County and high numbers run in Weston County. A large number of state highways are very short, less than 5 kilometers long. In addition, the height of the number says little about its importance, both low and high numbers are important roads and unimportant roads. In fact, the highest-numbered road, SR-789, is the state’s longest state highway, though double-numbered for three-quarters of its length with other roads. There are no single digit road numbers in Wyoming. The main numbering runs from 10 to 585 plus 789, however above 414 many numbers are skipped, and lower numbers are also frequently skipped, sometimes with more than 10 at a time. Some road numbers are also based on former US Highways. In some cases there are also state highways with a number that was planned to be renumbered as US Highway, which never happened.

Road number shield

The Wyoming road number shield consists of a yellow shield with a black frame, a black number and the silhouette of the Bucking Horse and Rider (BH&R), a Wyoming trademark. The logo has been used since 1918, and coincides with the nickname ‘Cowboy State’. It has also been used on license plates in Wyoming since 1936.

Traffic intensities

WYO 77 only has 20 vehicles per day.

Wyoming is characterized by quiet to extremely quiet roads. In the largest cities, there are rarely more than 20,000 vehicles on the highway. Traffic jams are a rare exception and can generally be traced back to incidents or road works. Long stretches of I-25 and I-90 in northeastern Wyoming have fewer than 5,000 vehicles per day. Hardly anywhere in the United States are intensities as low as in Wyoming. The lowest intensity on an Interstate Highway is on I-90 at Buffalo, immediately east of the interchange with I-25, where only 2,200 vehicles travel per day. This is because traffic to Buffalo from Gillette has already turned off shortly before, leaving only transit traffic.

Freight traffic

The main through traffic corridor is I-80 through the south of the state. This is part of a transcontinental route, with the advantage that it does not go as high as Interstate 70 in Colorado and therefore easier for truck traffic. The disadvantage of the route through Wyoming is the often strong winds and difficult driving conditions in the winter. I-80 handles 5,000 to 6,000 trucks a day on most routes. In contrast, I-25 between Casper and Buffalo only uses 700 trucks a day. Also on the I-90 between Buffalo and Gillette there are similar numbers of trucks.

Wyoming Road Network