Utah Road Network

By | October 13, 2022

Utah’s road network.

The road network in Utah is very thin, especially in the west. There are only a few paved roads in an area of 200 by 500 kilometers. The greatest concentration of roads is, of course, in the Salt Lake City region, and a corridor between I-15 and US 89 through the center and south of the state.

Road management

The state highway authority is the Utah Department of Transportation, abbreviated UDOT. UDOT operates 5,887 kilometers of state highway, a small network for the large size of the state. UDOT has its origins in the State Road Commission of Utah which was established in 1909. In 1975 this merged into the current Utah Department of Transportation.

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

Interstate Highways

Interstate 15 is the north-south route, and Interstate 80 is the main east-west route. Both roads converge in the Salt Lake City metropolitan area. To the north runs Interstate 84, which provides throughput for traffic from the Salt Lake City area to cities such as Portland and Seattle. Interstate 70 runs through the central part of the state, leading to Denver, Colorado.

There is one 3-digit Interstate Highway, Interstate 215, which is Salt Lake City’s bypass. The only remaining highway is SR-201 in the same city. There are no facilities for 180 kilometers on Interstate 70 between Salina and Green River. Interstate 80 has the longest stretch between two exits in the Bonneville Salt Flats, namely 60 kilometers. The highway here also runs straight for 70 kilometers in a row.

The Interstate 15 corridor is a 160-kilometer-long urbanized area along the Rocky Mountains, spread over 4 counties with 2.4 million inhabitants. I-15 was considerably widened in this corridor between 2000 and 2020 and since then has 10 or more lanes over a large distance. The longest continuous HOV lanes in the United States can also be found here. Some of these are also express lanes.

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

US Highways

The underlying road network is formed by US Highways that often run through very remote areas and where driving is not without risk. For example, the US 6 runs from Delta for 140 kilometers to the border with Nevada without even passing a single village. Of particular interest are US 6 between Spanish Fork and Green River, which handles through traffic from Salt Lake City to Denver here, and US 50, which is of particular importance because there are no alternate roads into central Nevada. US 191 is eastern Utah’s primary north-south route.

State Highways

In 2013, there were 5,887 kilometers of State Highways in Utah. These make up the secondary road network, but because the main road network is very thin, they are often the only through paved roads in vast areas, especially in southern Utah. The State Highway network was developed in the 1920s, but many routes were scrapped in 1962 and 1977. Before 1977, numbers SR-1 through SR-9 belonged to the Interstate Highways and US Highways that served Utah. These were really just administrative numbers, similar to Georgia or Florida.

There have been no double numberings within the network since 1977. In a place where two routes run on the same road, only one number is signposted. A prominent example is the route of I-84 between Tremonton and Ogden, which is only signposted as I-15.

Toll roads

There are no general toll roads in Utah. However, near Ogden there is the private road Adams Avenue Parkway, for which toll has to be paid.


I-70 through the San Rafael Swell.

The first roads

On March 23, 1909, the State Road Commission was established. At that time, a network of state roads was already established. Utah was relatively early in establishing an agency responsible for road construction. This was only made mandatory with the Federal Aid Road Act of 1916. Utah’s first state highway network was radial in nature, mostly to and from Salt Lake City or the Provo area. In the first road structure, the later US 89 and US 91 were already designated as primary north-south routes of the state, as well as US 40 as the east-west route. There were actually no roads at all in the western half of Utah. It was planned in the early 20th century that the east-west connection to Salt Lake City would run north of the Great Salt Lake.

The first major road project was the Wendover Cut-off, a new road link through the Bonneville Salt Flats that formed a much shorter route to Wendover on the Nevada border. This road opened in stages between 1917 and 1925, but was unpaved at the time.

In the early 1920s, the first road numbering was introduced in Utah. US Highways were added in 1926. When the US Highways were introduced, Utah had only one longer tarmac road, a 150-mile stretch of US 91 between Nephi, Provo, Salt Lake City, Ogden, and Brigham City. At the time, this was already the most populous region of the state. Outside there were very few paved roads, mostly no more than a small number of passages through villages.

The asphalting of the main roads

At the end of the 1920s, the main roads were actively asphalted, especially in the first half of the 1930s a large part of the US Highways was asphalted and by 1940 almost all major roads were paved. As in many states, this was used to fight the economic depression to keep people employed through the New Deal. This was a phenomenon that occurred in many states west of the Mississippi River, as this part of the United States had few paved roads.

Utah had only a thin network of paved roads until after World War II. Large areas had no improved roads at all. Population density was also very low outside the Wasatch Front. Western Utah in particular was undeveloped, only US 40 was a through route here. During that period there was a battle between Nevada and Utah over the route of the US 50. The state of Utah preferred a northern route via Wendover, the state of Nevada preferred a more southern route via Ely. Until the 1950s, US 40 and 50 west of Salt Lake City were double-numbered along the same route. In 1952, a new road from Ely to Delta in Utah opened as the third paved road between Nevada and Utah. With that, US 50 was moved quite a bit south. This would later happen again in central Utah, when US 50 was routed on I-70 instead of taking the detour via Spanish Fork and US 6.

After 1950, only a limited number of US Highways were unpaved or missing. US 163 was not built by Monument Valley until the early 1950s. Before that, there was no road connection between Utah and Arizona in a very large region. Between 1957 and 1959, a 100-mile new route of US 89 from Kanab to Page in Arizona was constructed in southern Utah, to coincide with the construction of the Glen Canyon Dam in Arizona. The last new US Highway built was the southernmost portion of US 191 between Bluff and Arizona, which was not opened until 1981 by the Navajo Indian Reservation.

Construction of the Interstate Highways

Before the creation of the Interstate Highway system in 1956, Utah had no real highways. However, significant parts of the US 89/91 corridor through the Wasatch Front had been widened to at least 4 lanes, including a highway-like section on the north side of Salt Lake City that later became part of I-15. Sometimes thought of as Utah’s first highway, it opened to traffic in 1956. The first stretch of newly constructed Interstate Highway was a stretch of Interstate 84 in the north of the state that opened in 1959.

In the original plans for the Interstate Highways, only four Interstate Highways were envisioned: I-15 as a north-south route, I-80 as an east-west route, I-84, but only west of Tremonton as a branch of I-15 towards Idaho and Oregon, plus I-215 as Salt Lake City beltway. In 1957, the eastern portion of I-84 between Ogden and Echo was also added to the plans so that through traffic from I-80 to the northwestern United States would not have to pass through Salt Lake City.

I-70 was originally planned no further west than Denver, Colorado. Because of the Rocky Mountains, construction costs were considered too high and traffic too low for a further extension of I-70. However, the states of Utah and Colorado agreed to do so, with Utah’s commitment that I-70 would follow the US 6 corridor to Spanish Fork, so that I-70 would form a connection between Denver and Salt Lake City. However, the federal government wanted a route to I-15 at Cove Fort, connecting Denver to the southwestern United States. In the end, it was decided for this variant.

The construction of the Interstate Highways progressed at a rapid pace, between 1960 and 1975 a large part of the highways was built. Special was the construction of I-70 between Salina and Green River, which passed through a completely undeveloped area, where there were no roads or villages at all. This was also the largest opening of an Interstate Highway ever, on December 5, 1970 113 kilometers of I-70 opened through the San Rafael Swell, one of the most spectacular stretches of highway in the United States. At the time, parts of the route were still single lanes due to the extremely low traffic volumes. It has only been since 1990 that I-70 has been continuously operated in 2×2 lanes.

All Interstate Highways had one missing link that opened relatively late. The last part of I-15 at Tremonton opened in 1990, the last part of I-70 at Richfield opened in 1989, the last part of I-80 in Salt Lake City opened in 1986, the last part of I-84 at Tremonton opened in 1986 and the last section of I-215 around Salt Lake City opened in 1989.

In particular, between 1997 and 2002, I-15 in Salt Lake City was renovated and drastically widened for the 2002 Olympic Games, which were held in Salt Lake City. Later, I-15 south of Salt Lake City was also significantly widened, through 2020 a longer stretch between Provo and Salt Lake City was widened to 2×6 lanes. In 2008 the new Legacy Parkway opened. The goal is to eventually create two parallel highways so that the urban row becomes less dependent on I-15.

Traffic intensities

Utah’s busiest stretch of road is the double-number I-15/I-80 in Salt Lake City, off State Route 201, where 252,000 vehicles drove daily in 2011. Various other sections of I-15 around Salt Lake City also handle more than 200,000 vehicles per day. Outside the region, however, traffic intensities are very low. I-70 handles fewer than 10,000 vehicles everywhere, and large portions of I-15, I-80, and I-84 also handle fewer than 25,000 vehicles per day, often less than 10,000 vehicles at state lines.


I-80 in Salt Lake City.

The only significant metropolitan area in Utah is the city row along the Wasatch Range, of which Salt Lake City is the largest city. Over a distance of about 100 miles, here is urbanization collectively referred to as the Wasatch Front. The 4 counties in this area together counted 2,411,000 inhabitants in 2019 and are growing rapidly.

In the south of Utah, the region around St. George is growing very quickly, in 1970 Washington County had 17,000 inhabitants, in 2019 it was 177,000 inhabitants.

Utah Road Network