Interstate 84 (I-84) is a part of the
Interstate Highway System
The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, or the Eisenhower Interstate System, is a network of controlled-access highways that forms part of the National Hi ...
that links
Portland, Oregon
Portland ( ) is the List of cities in Oregon, most populous city in the U.S. state of Oregon, located in the Pacific Northwest region. Situated close to northwest Oregon at the confluence of the Willamette River, Willamette and Columbia River, ...
, to
I-80
Interstate 80 (I-80) is an east–west transcontinental freeway that crosses the United States from San Francisco, California, to Teaneck, New Jersey, in the New York metropolitan area. The highway was designated in 1956 as one of the ori ...
near
Echo, Utah. The segment in the US state of
Utah
Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...
is the shortest of any of the three states the western I-84 passes through and contains the eastern terminus of the highway. I-84 enters
Box Elder County near
Snowville before becoming
concurrent with
I-15 in
Tremonton. The concurrent highways travel south through
Brigham City and
Ogden and separate near
Ogden-Hinckley Airport. Turing east along the
Davis County border, I-84 intersects
US Route 89 (US-89) and enters
Weber Canyon as well as
Morgan County. While in Morgan County, I-84 passes the
Devil's Gate-Weber Hydroelectric Power Plant and
Devil's Slide rock formation. Past
Morgan, the highway crosses into
Summit County, past the
Thousand Mile Tree before reaching its eastern terminus at I-80 near Echo.
Construction of the
controlled-access highway
A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms ...
was scheduled in late 1957 under the designations Interstate 82S (I-82S) and Interstate 80N (I-80N). The I-82S designation was only applied on paper for about a year, but the I-80N designation was the highway's official designation until 1977 when it was renumbered I-84 by the
(AASHTO). By 1986, construction of the freeway had been completed across the three states.
Average traffic in 2012, along the non-concurrent parts of I-84, ranged from as few as 6,655 vehicles traveling along I-84 at the interchange with
State Route 86 (SR-86) in
Henefer, and as many as 18,945 vehicles used the highway at the
SR-26 interchange in
Riverdale.
Route description
Out of the three states that the western portion of I-84 passes through, the segment in Utah is the shortest. By comparison, the longest stretch of western I-84 through a single state is the segment in
Oregon
Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...
. I-84 also has a noncontiguous
eastern segment that passes through Pennsylvania, New York, Connecticut, and Massachusetts: all four of these segments are shorter than the Utah segment.
Every year, the
Utah Department of Transportation
The Utah Department of Transportation (UDOT) is an agency of the state government of Utah, United States; it is usually referred to by its initials UDOT (pronounced "you-dot"). UDOT is responsible for approximately 5,900 miles (9,495 kilomet ...
(UDOT) conducts a series of surveys on its highways in the state to measure traffic volume. This is expressed in terms of
annual average daily traffic (AADT), a measure of traffic volume for any average day of the year. In 2012, UDOT calculated that as few as 6,655 vehicles traveled I-84 at the interchange with
SR-86 in
Henefer, and as many as 18,945 vehicles used the highway at the
SR-26 interchange in
Riverdale.
Between 27 and 57 percent of the traffic recorded consisted of trucks.
These counts are of the portion of the freeway in Utah and are not reflective of the entire Interstate or of its
concurrency with I-15. As part of the
Interstate Highway System
The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, or the Eisenhower Interstate System, is a network of controlled-access highways that forms part of the National Hi ...
, the entire route is listed on the
National Highway System, a system of roads that are important to the nation's economy, defense, and mobility.
Western segment
Crossing the Idaho–Utah state line, I-84 enters
Box Elder County and the
Curlew Valley near farmland that utilizes
center-pivot irrigation before intersecting
SR-30 at a
diamond interchange
A diamond interchange is a common type of road junction, used where a controlled-access highway crosses a minor road.
Design
The freeway itself is grade separation, grade-separated from the minor road, one crossing the other over a bridge. ...
.
The town of
Snowville is crossed before passing to the north of the
Hansel Mountains and the
North Promontory Mountains. The town of
Howell, accessible from an interchange with
SR-83, lays to the southeast of
Blue Creek Reservoir in the
Blue Creek Valley. Access to
Golden Spike National Historical Park is provided by SR-83 south of Howell. The
Blue Spring Hills form the southern border of Howell as I-84 continues southeast.
Additional center irrigation farmland is passed before giving way to more traditional farmland outside of the city of
Tremonton,
where a
trumpet interchange
In the field of road transport, an interchange (American English) or a grade-separated junction (British English) is a road junction that uses grade separations to allow for the movement of traffic between two or more roadways or highways, usi ...
marks where
I-15 turns north towards
Malad City and
Pocatello.
Heading southeast from this interchange, I-84 and I-15 are concurrent for just over .
Concurrency with I-15

Concurrent highways I-15/I-84 continue south, parallel to rail belonging to the
Union Pacific Railroad
The Union Pacific Railroad is a Railroad classes, Class I freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Pacific is the second largest railroad in the United Stat ...
past the
Wellsville Mountain Wilderness, to an interchange at 1100 West in
Brigham City, also known as
US-91, which, once in Brigham City, becomes concurrent with
US-89 and the two highways travel northeast from Brigham City into
Box Elder Canyon toward
Logan in the heart of the
Cache Valley. US-89 closely parallels I-15/I-84 east, as the highways pass
Willard Bay,
Willard Bay State Park, and
Bear River Migratory Bird Refuge before crossing into
Weber County.
Upon entering Weber County, the rail line that the highway has paralleled since Tremonton splits off eastward near
Defense Depot Ogden, as the concurrent highways continue south past
Farr West and
Marriott-Slaterville before a
Southern Pacific Railroad
The Southern Pacific (or Espee from the railroad initials) was an American Railroad classes#Class I, Class I Rail transport, railroad network that existed from 1865 to 1996 and operated largely in the Western United States. The system was oper ...
rail line, which traverses the
Great Salt Lake
The Great Salt Lake is the largest saltwater lake in the Western Hemisphere and the eighth-largest terminal lake in the world. It lies in the northern part of the U.S. state of Utah and has a substantial impact upon the local climate, partic ...
on a
causeway
A causeway is a track, road or railway on the upper point of an embankment across "a low, or wet place, or piece of water". It can be constructed of earth, masonry, wood, or concrete. One of the earliest known wooden causeways is the Sweet T ...
, crosses under the freeway. The city of
Ogden is bypassed by the Interstates, with US-89 serving downtown. US-89 is accessible via interchanges with
SR-39,
SR-79, and
SR-104 in addition to I-84 further southeast. I-84 splits from I-15 at the south end of
Ogden-Hinckley Airport, with I-15 continuing south toward
Salt Lake City
Salt Lake City, often shortened to Salt Lake or SLC, is the capital and most populous city of the U.S. state of Utah. It is the county seat of Salt Lake County, the most populous county in the state. The city is the core of the Salt Lake Ci ...
and
Provo.
Eastern segment

Splitting from I-15 near
Roy, I-84 passes between
Hill Air Force Base
Hill Air Force Base is a major U.S. Air Force (USAF) base located in Davis County, Utah, just south of the city of Ogden, and bordering the Cities of Layton, Clearfield, Riverdale, Roy, and Sunset with its largest border immediately adja ...
, which is to the south of the highway, and
Washington Terrace before clipping the extreme northern portions of
Davis County.
While in Davis County, I-84 intersects 475 East, also known as the
Adams Avenue Parkway,
before coming to a hybrid
partial cloverleaf
A partial cloverleaf interchange or parclo is a modification of a cloverleaf interchange.
The design has been well received, and has since become one of the most popular freeway-to-arterial road, arterial Interchange (road), interchange designs ...
/
half diamond interchange with US-89 along the Davis–Weber county line.
I-84 follows the
Weber River
The Weber River ( ) (Shoshone: Ho-o-pah) is a long river of northern Utah, United States. It begins in the northwest of the Uinta Mountains and empties into the Great Salt Lake. The Weber River was named for American fur trapper John Henr ...
into
Weber Canyon,
Morgan County, and
Wasatch–Cache National Forest. Once in the canyon, the carriageways of the highway split to accommodate the
Devil's Gate-Weber Hydroelectric Power Plant. Following the river south, I-84 exits the forest and enters the
county seat
A county seat is an administrative center, seat of government, or capital city of a county or parish (administrative division), civil parish. The term is in use in five countries: Canada, China, Hungary, Romania, and the United States. An equiva ...
of
Morgan. Leaving the city the highway turns back east,
passing
Devil's Slide, an unusual rock formation just off the freeway.
Upon entering
Summit County, I-84 passes
Thousand Mile Tree, planted by Union Pacific Railroad workers to mark the construction of of rail from its origin in
Omaha, Nebraska
Omaha ( ) is the List of cities in Nebraska, most populous city in the U.S. state of Nebraska. It is located in the Midwestern United States along the Missouri River, about north of the mouth of the Platte River. The nation's List of United S ...
.
The tree was said to be the only
pine tree between Omaha and Salt Lake City.
Another tree was planted as the original tree had died in 1900 and was removed in 1926 to during the conversion from
single-track to
double-track through the canyon. Past the tree, the freeway passes through the town of Henefer before terminating at a
directional T interchange with I-80 just south of the
census-designated place
A census-designated place (CDP) is a Place (United States Census Bureau), concentration of population defined by the United States Census Bureau for statistical purposes only.
CDPs have been used in each decennial census since 1980 as the counte ...
of
Echo
In audio signal processing and acoustics, an echo is a reflection of sound that arrives at the listener with a delay after the direct sound. The delay is directly proportional to the distance of the reflecting surface from the source and the lis ...
. Immediately south of the interchange is Echo Reservoir and
Echo Dam.
History
Earlier roads
Most of the original routing of what is now I-84 existed as early as 1923; however, the portion of now I-84 into Idaho was not yet constructed.
In 1926, much of the route was signed as
US-30S, from the now eastern terminus at I-80 (
US-530 then), northwest into Ogden. Between Ogden and Brigham City, the highway was to be concurrent with US-91, then US-30S split off northwest to the Idaho border.
The entire western branch of US-30S was an
unimproved road; however, the concurrency into Ogden was paved. The remainder of the route to its now terminus was mostly
graded with a few
improved sections,
and, by 1937, the entire route was paved.
Current road
The first Utah state route to have the
number 84 is what is now known as
SR-126. SR-126 was originally numbered SR-84 until the
1977 Utah state route renumbering. Previously, the freeway's legislative designation was SR-3.
Like the other two main Interstate Highways in Utah, I-15 (Veterans Memorial Highway) and I-80 (Purple Heart Trail), I-84 has also been given a special name of "Vietnam Veterans Memorial Highway". House Bill HB275, sponsored by Utah Representative Justin Fawson, North Ogden, authorizing the name designation was signed into law by Utah Governor
Gary Herbert on March 30, 2015.
The highway loosely follows the path of the
first transcontinental railroad
America's first transcontinental railroad (known originally as the "Pacific Railroad" and later as the "Overland Route (Union Pacific Railroad), Overland Route") was a continuous railroad line built between 1863 and 1869 that connected the exis ...
.
The original routing of US-30S had the highway passing into Idaho west of Black Pine Peak; however,
the new I-84 was constructed to the east. The original roadways are now numbered SR-30, Utah State Route 42, SR-42 and Idaho State Highway 2847.
Passage of the Federal-Aid Highway Act of 1956 formed the Interstate Highway System;
however, only the western segment of now I-84 was approved at this time, and a designation of I-82S was assigned to a then unconstructed
controlled-access highway
A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms ...
across Box Elder County in 1957.
The eastern segment of the highway was added later in 1957, and the route was numbered I-80N by 1958.
By 1968, portions of the western half of the freeway had been completed, along with the segment between Tremonton and Brigham City. A portion of the freeway was completed around Morgan as well.
By 1971, most of the western portions of the freeway had been constructed with two sections remaining that had at-grade intersections. Along the concurrency, there were gaps between Brigham City and Pleasant View and one small gap near the Devil's Slide.
The I-80N designation was changed to I-84 in 1977 by the American Association of State Highway and Transportation Officials, AASHTO, over objections from the Washington State Department of Transportation and the Idaho Transportation Department, and with the support of UDOT and the Oregon Department of Transportation.
By 1978, construction of I-84 was complete across most of the three states. In September 1986, the final section of the highway was opened on the from
Tremonton to Blue Creek Summit, following three years of construction that cost $21 million (equivalent to $ in ).
[ ]
In 1994, I-84 was planned to be used to transport low-level radioactive waste from Idaho National Laboratory to the Waste Isolation Pilot Plant in Carlsbad, New Mexico, via Wyoming.
This did not start until 1999 however due to the delay in the opening of the New Mexican plant.
A $20-million (equivalent to $ in ) reconstruction of the US-89 interchange at the mouth of Weber Canyon was financed partly by the funding obtained by the state in preparation for the 2002 Winter Olympics in 1998
and was scheduled to begin in 2000.
Reconstruction of a segment of I-84 between Mountain Green, Utah, Mountain Green and Morgan was done between 2004 and 2005 at a cost of $19 million (equivalent to $ in ).
One of the sub-contractors on the job was found guilty of lying about sub-par work done on installation of roadside impact absorbers along this stretch.
Exit list
See also
*
*
References
External links
*
Interstate 84 in Utahon AARoads
{{DEFAULTSORT:Interstate 84 In Utah
Interstate Highways in Utah, 84
Interstate 84 (Oregon–Utah), Utah
Transportation in Box Elder County, Utah
Transportation in Weber County, Utah
Transportation in Davis County, Utah
Transportation in Morgan County, Utah
Transportation in Summit County, Utah
Central Overland Route
U.S. Route 30S