Interstate 84 in Idaho

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Interstate 84

Vietnam Veterans Memorial Highway
I-84 highlighted in red
Route information
Maintained by ITD
Length275.650 mi[1] (443.616 km)
NHSEntire route
Major junctions
West end I-84 at Oregon state line
Major intersections
East end I-84 at Utah state line
CountryUnited States
CountiesPayette, Canyon, Ada, Elmore, Gooding, Jerome, Minidoka, Cassia, Oneida
Highway system
  • Idaho State Highway System
SH-81 I-86

Interstate 84 (I-84) in the U.S. state of Idaho is a major Interstate Highway that traverses the state from the Oregon state line in the northwest to Utah state line in the southeast. It primarily follows the Snake River across a plain that includes the cities of Boise, Mountain Home, and Twin Falls. The highway is one of the busiest in Idaho and is designated as the Vietnam Veterans Memorial Highway.

I-84 runs for 276 miles (444 km) within Idaho, beginning near Ontario, Oregon, and traveling concurrent with several U.S. routes through the Boise metropolitan area and Mountain Home towards Twin Falls. I-84 splits away from US 30 and the Snake River at a junction with I-86 near Declo, where it turns southeast to cross the Sublett Range into northern Utah. The highway has an auxiliary route, I-184, which serves downtown Boise.

Route description

I-84 is the longest Interstate highway in Idaho, running for 276 miles (444 km) and connecting several of the state's largest metropolitan areas. It has a single auxiliary route, I-184 in Boise, and several business routes.[2] The highway was officially designated as the Vietnam Veterans Memorial Highway in 2014, mirroring the name for Oregon's section of I-84.[3][4] The Idaho section of I-84 is maintained by the Idaho Transportation Department (ITD), which conducts an annual survey of traffic on certain highway segments that is expressed in terms of average annual daily traffic (AADT), a measure of traffic volume for any average day of the year. Average daily traffic volumes on I-84 in 2018 ranged from a minimum of 9,552 vehicles near Sweetzer Summit and 139,113 vehicles at I-184 in western Boise.[5]

Boise and Treasure Valley

Looking eastbound on I-84 in Boise, approaching the terminus of I-184

I-84 enters the state of Idaho after crossing the Snake River from Ontario, Oregon, west of Fruitland, Idaho. The four-lane freeway travels southeast along the Snake River and passes an eastbound-only rest area and visitors center, which mirrors a westbound facility on the Oregon side of the river.[6] Its first interchange is with US 95, the primary north–south highway in Idaho, at Palisades Corner south of Fruitland. I-84 continues southeast across farmland in the Snake River Plain and straddles the edge of a hill. South of New Plymouth the freeway intersects and becomes concurrent with US 30. The paired highways continue south along the side of a hill and cross into Canyon County northeast of Notus.[7][8]

The freeway enters the Treasure Valley, which also constitutes much of the Boise metropolitan area, near the outskirts of Caldwell and intersects State Highway 44 (SH-44), which continues east to Middleton and Eagle. Shortly before crossing the Boise River into Downtown Caldwell, I-84 and US 30 begin a brief concurrency with US 20 and US 26, with both continue west towards Parma and the Oregon state border.[8] The freeway skirts the north side of Downtown Caldwell, which is served by a designated business route, and passes through residential neighborhoods before US 20 and US 26 split off and travel east onto Franklin Road. I-84 and US 30 continue southeast through an industrial area and pass the Caldwell Industrial Airport and Karcher Mall before reaching the city of Nampa. The six-lane freeway travels through an industrial area on the northwestern side of Nampa, parallel to a set of railroad tracks, but turns east to bypass the city center. SH-55 joins the concurrency at an interchange with Karcher Road and I-84 Business returns to the freeway at an interchange located near Nampa Gateway Center, the Nampa campus of the College of Western Idaho, and the Ford Idaho Center.[7][8]

I-84 expands to eight lanes as it leaves Nampa and enters Ada County, passing through suburban neighborhoods in Meridian.[9] The freeway crosses under two single-point urban interchanges at Ten Mile Road and SH-69, along with a partial cloverleaf interchange where SH-55 splits from the concurrency to head north.[10] I-84 enters the city of Boise and expands to ten lanes before an interchange with I-184, an auxiliary route that travels into Downtown Boise. I-84 turns southeast and travels around the city's outer residential neighborhoods, passing the main terminal at Boise Airport and a nearby industrial area. The freeway is rejoined by US 20 and US 26 before leaving Boise, climbing out of Treasure Valley by following Fivemile Creek over a barren plateau.[7][8]

Mountain Home and Magic Valley

I-84 eastbound, approaching Mountain Home

The highway crosses into Elmore County and rejoins the Union Pacific Railroad's Nampa Subdivision as it passes the Morley Nelson Snake River Birds of Prey National Conservation Area.[11] I-84 then travels around the city of Mountain Home, while a signed business route serves the city center and leads to the nearby Mountain Home Air Force Base. On the east side of the city, I-84 intersects SH-51 and ends its concurrency with US 20, which continues east towards Sun Valley, Idaho Falls, and Yellowstone National Park.[8] I-84, US 26, and US 30 continue southeast through the conservation area and descends from the plateau into the Snake River Plain. The freeway travels around the north side of Hammett, which is served by a business route that connects to SH-78, and reaches the Snake River.[7][8]

I-84 travels upstream along the north bank of the Snake River to Glenns Ferry, where it bypasses the town and Three Island Crossing State Park. The freeway crosses over the river twice east of Glenns Ferry to avoid a bend in the river, which is followed by the railroad. After entering Gooding County, I-84 reaches the town of Bliss, where US 30 and US 26 both split from the freeway and end their concurrency. US 30 travels south along the Snake River towards Hagerman, while US 26 runs east across the plains to Gooding and Craters of the Moon National Monument and Preserve.[8] The freeway continues southeast and crosses 250 feet (76 m) over the Mallad Gorge (part of Thousand Springs State Park) on a pair of level bridges.[12] I-84 then passes through farmland on the edge of a lava plain while following an abandoned railroad right of way to Wendell, where it intersects SH-46.[7]

The freeway travels around the south side of Wendell and turns east to follow an active railroad through a rural area that marks the boundary of Jerome County. I-84 reaches the county seat, also named Jerome, and turns southeast after intersecting SH-25 to bypass the city. The interstate intersects SH-79 on the south side of Jerome and reaches a partial cloverleaf interchange with US 93 across the Snake River Canyon from the city of Twin Falls. I-84 then proceeds eastward through the rural Magic Valley, staying on the north side of the Snake River. It intersects SH-50 at Tipperary Corner and bends south around Skeleton Butte and a municipal airport in Hazelton. Between Hazelton and the Minidoka County line, I-84 is concurrent with SH-25, which continues along the north side of the valley.[7][8]

Southeastern Idaho

I-84 passes north of Burley, intersecting SH-27 near Paul. At a partial cloverleaf interchange in northeastern Heyburn, the freeway intersects SH-24 and is rejoined by US 30, beginning a new concurrency as the highway leaves the Magic Valley. I-84 crosses over the Snake River into Cassia County and intersects SH-25 and SH-25 at an interchange on the east bank of the river near Declo. Near the Minidoka National Wildlife Refuge, I-84 reaches the western terminus of I-86, which carries US 30 and follows the Snake River upstream to American Falls and Pocatello. I-84 turns southeast from the interchange and continues into the Raft River Valley, running parallel to SH-81 near Horse Butte in view of the Cotterel Mountains.[7][8]

After crossing the rural valley, I-84 begins following Meadow Creek and climbs into Mortenson Canyon, which marks the northeastern extent of the Black Pine Mountains. The highway crests at Sweetzer Summit, located 5,522 feet (1,683 m) above sea level, and descends into the Juniper Valley on the south side of the Sublett Range in Sawtooth National Forest.[13][14] I-84 continues southeast across the valley, passing a set of rest areas in Oneida County, and reaches the Utah state border northwest of Snowville.[7][8] The freeway continues into Utah and passes through Ogden before terminating at a junction with I-80 in the Wasatch Range.[15]


Prior to the construction of I-84, the corridor was served by Idaho State Highway 2 and Route A of the Sampson Trails system.[2][16] U.S. Route 30 was created in 1926 under the national numbered highway system, traveling through southern Idaho along the historic Oregon Trail. Near Declo, US 30 split into two routes: U.S. Route 30N, following the Snake River to Pocatello, and U.S. Route 30S, providing a shorter connection to the Salt Lake City area.[17]

The Interstate highway was initially designated in 1957 as Interstate 82, but was renumbered as Interstate 80N in 1958 to correspond with US 30.[18]

The route of I-80N between Nampa and Boise was selected in 1958 as one of eight proposals and completed in stages between 1965 and 1968.[19][20] Rural sections in southwestern Idaho had already been completed by the mid-1960s, connecting Ontario, Oregon, to Caldwell, and Boise to Mountain Home.[19] The 6.6-mile (10.6 km) Nampa–Meridian section opened to traffic on September 29, 1965.[21] Another 4.5 miles (7.2 km) from SH-69 in Meridian to western Boise opened on December 12, 1968, at a cost of $9.5 million.[22] The freeway was extended west from Nampa to Caldwell on December 21, 1966, filling a gap in Interstate 80N and connecting to an already-completed rural section.[23] The 11.1-mile (17.9 km) bypass around southeastern Boise was opened on December 1, 1969. It cost $7.13 million to construct and included five interchanges.[24] Another section was opened around the same time in Sublett in eastern Cassia County, which caused the killing of eighteen mule deer from a local herd from collisions with drivers within the first six weeks.[25]

Renumbering and reconstruction

On May 1, 1980, I-80N was renumbered to I-84 to eliminate confusion with the western section of the non-suffixed I-80, which split from I-80N in Salt Lake City and continued west to San Francisco.[26] The change was approved by AASHTO in July 1977 and resulted in the replacement of 1,000 signs along the freeway in Idaho.[27][28]

Several rest areas on I-84 were closed in 1992 due to budget cuts and maintenance issues and their restoration was dependent on several federal highway bills that were never passed.[29]

To address increasing traffic congestion in the Boise metropolitan area, fueled by population growth and suburban development, the Idaho Transportation Department (ITD) has widened 24 miles (39 km) of I-84 with funds from a bond sale approved by the state legislature in 2005.[30][31] A six-mile (10 km) section between eastern Nampa and Meridian was widened to six lanes in October 2009 and eight lanes in August 2011 as part of a $113 million expansion project.[32][33] The agency has also built several single-point urban interchanges (SPUIs) in Meridian and Boise to improve efficiency.[10][34]

Construction of a widened eight-lane section of I-84 through Nampa began in July 2019 and was completed two years later at a cost of $150 million.[35][36] The project included several new overpasses and rebuilt interchanges—including one SPUI—from Franklin Boulevard to Karcher Road (SH-55).[37][38] A second phase to expand the freeway to six lanes for four miles (6.4 km) through Caldwell began construction in 2021 and is expected to be completed in August 2023 at a cost of $300 million.[39][40] Further work, extending northwest to the SH-44 interchange near Middleton, is under design and study as of 2021.[36]

In 2017, the ITD also began work to resurface and restore fifteen bridges on I-84 that had deteriorated over their lifespan. The project also included pavement repair and improvements on 21 miles (34 km) of the highway in the Magic Valley region.[41]

In 2014 and 2019, because of increased speeds and the installation of new interchanges at Declo and Twin Falls, the ITD closed the Jerome rest area and extended the Cotterell rest area to make way for a new weigh station.[42][43] To remedy this Idaho joined the Interstate Oasis Program and opened three truck stops in Twin Falls and Jerome.[44]

Exit list

I-84 west – Portland
Continuation into Oregon
2.8764.6283 US 95 – Parma, Fruitland, Payette
US 30 west – Emmett, New Plymouth
West end of US-30 overlap
12.90620.77013Black Canyon Junction
Canyon17.33527.89817Sand Hollow
24.83939.97425 SH-44 – Middleton

US 20 west / US 26 west – Parma, Notus
West end of US-20/US-26 overlap

I-84 BL east to SH-19 – Caldwell, Wilder, Homedale
27.62044.4502810th Avenue – Caldwell City Center

US 20 east / US 26 east (Franklin Road)
East end of US-20/US-26 overlap
SH-55 south / Midland Boulevard – Nampa, Marsing
West end of SH-55 overlap
34.96556.27135Northside Boulevard
35.98557.91236Franklin Boulevard
I-84 BL west (Garrity Boulevard) – Nampa, Murphy
Ada42.00067.59242Ten Mile Road
Meridian44.00770.82244 SH-69 – Meridian, Kuna
SH-55 north – McCall, Eagle
East end of SH-55 overlap
I-184 east / Franklin Road – City Center
Left exit eastbound; I-184 exit 0
50.14080.69350Cole Road / Overland RoadSigned as exits 50A (Overland Rd. west) and 50B (Cole/Overland) eastbound, and 50A (Cole/Overland) and 50B (Overland Rd. east) westbound
51.99783.68152Orchard Street
53.48386.07353Vista Avenue – Boise Airport
US 20 / US 26 west (Broadway Avenue)
West end of US-20/US-26 overlap
56.93291.62357 SH-21 (Gowen Road) – Idaho City
59.51095.77259S. Eisenman Road / Memory RoadSigned as exits 59A (S. Eisenman Rd.) and 59B (Memory Rd.) eastbound
63.517102.22164Blacks Creek Road – Kuna
70.772113.89671Mayfield, Orchard
Elmore74.333119.62774Simco Road

I-84 BL east to SH-51 / SH-67 – Mountain Home, Bruneau
Eastbound signage
West Mountain HomeWestbound signage

US 20 east (Sun Valley Highway) / I-84 BL west / SH-51 south (American Legion Boulevard) to SH-67 – Mountain Home, Fairfield
East end of US-20 overlap
99.570160.24299Old Oregon Trail Road – Mountain Home

I-84 BL east to SH-78 – Hammett

I-84 BL west to SH-78 / Cold Springs Road – Hammett
Westbound exit and eastbound entrance
I-84 BL east – Glenns Ferry
Eastbound exit and westbound entrance
I-84 BL west – King Hill, Glenns Ferry
125.159201.424125Paradise Valley
128.993207.594129King Hill

I-84 BL east / US 30 east / Pioneer Road – Buhl, Bliss
East end of US-30 overlap

I-84 BL west / US 26 east to US 30 – Gooding, Hagerman, Bliss
East end of US-26 overlap
To SH-46 – Wendell, Hagerman
156.581251.993157 SH-46 – Gooding, Wendell
Jerome165.160265.799165 SH-25 – Jerome
Jerome168.010270.386168 SH-79
173.013278.437173 US 93 – Twin Falls, Sun ValleyMain exit into Twin Falls via the Perrine Bridge
181.930292.788182 SH-50 – Kimberly, Eden, Twin Falls
188.301303.041188Valley Road – Hazelton, Eden
SH-25 west (Ridgeway Road) – Hazelton
West end of SH-25 overlap
county line
SH-25 east / Kasota Road – Paul
East end of SH-25 overlap
I-84 BL east / SH-27 – Paul, Burley

I-84 BL west / US 30 west / SH-24 – Burley, Rupert
West end of US-30 overlap
Cassia216.395348.254216 SH-25 / SH-77 – Albion, Rupert, Declo

I-86 east / US 30 east to I-15 – Pocatello
Left exit eastbound; East end of US-30 overlap
To SH-81 / Yale Road – Malta, Declo
236.655380.859237Idahome Road
244.810393.984245Sublett Road – Malta
253.705408.299254Sweetzer Road
Oneida262.512422.472263Juniper Road
I-84 east – Ogden, Salt Lake City
Continuation into Utah
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


  1. ^ a b Idaho Transportation Department, Milepoint Log Reports Archived July 14, 2004, at the Wayback Machine
  2. ^ a b "Interstate 84 – Idaho". Idaho Transportation Department. May 2006. Archived from the original on September 1, 2010. Retrieved June 21, 2018.
  3. ^ Russell, Betsy (August 12, 2014). "I-84 now officially Vietnam Veterans Memorial Highway". The Spokesman-Review. Retrieved June 18, 2018.
  4. ^ "Idaho S1227: "Archived copy" (PDF). Archived from the original (PDF) on 2014-12-22. Retrieved 2014-08-14.{{cite web}}: CS1 maint: archived copy as title (link)"
  5. ^ "ATR & WIM Data: Interstate 84". Idaho Transportation Department. Retrieved April 21, 2019.
  6. ^ "Rest Area Map". Idaho Transportation Department. Retrieved March 14, 2019.
  7. ^ a b c d e f g h Google (March 14, 2019). "Interstate 84 (Idaho)" (Map). Google Maps. Google. Retrieved March 14, 2019.
  8. ^ a b c d e f g h i j Idaho State Highway Map (PDF) (Map). 1:1,248,000. Idaho Transportation Department. May 2017. Retrieved March 14, 2019.
  9. ^ "I-84 history remade". The Idaho Press-Tribune. October 30, 2009. p. 1.
  10. ^ a b Beech, Holly (September 6, 2015). "Meridian Interchange about 2 months away from completion". Idaho Press. p. 3. Retrieved April 19, 2019.
  11. ^ "Idaho Statewide Rail Plan" (PDF). Idaho Transportation Department. June 21, 2013. Retrieved April 20, 2019.
  12. ^ Weeks, Andrew (May 20, 2009). "Historic Malad Gorge popular outdoors spot". Times-News. Twin Falls, Idaho. Retrieved April 20, 2019.
  13. ^ Welch, Laurie (December 6, 2009). "Lonesome highway". Times-News. Twin Falls, Idaho. p. 5. Retrieved April 20, 2019.
  14. ^ Cothern, Mike (September 1, 2011). "A Lesser Known Mountain Range Offers Hikers Birds-eye View of Great Salt Lake". Times-News. Twin Falls, Idaho. Retrieved April 20, 2019.
  15. ^ Utah Official Highway Map (Map). Utah Department of Transportation. 2017. OCLC 1056775025. Retrieved April 20, 2019.
  16. ^ 1926 map of Southern Idaho
  17. ^ Bureau of Public Roads & American Association of State Highway Officials (November 11, 1926). United States System of Highways Adopted for Uniform Marking by the American Association of State Highway Officials (Map). 1:7,000,000. Washington, DC: United States Geological Survey. OCLC 32889555. Retrieved November 7, 2013 – via Wikimedia Commons.
  18. ^ "Interstate 82N Changed to 80N". Idaho State Journal. Pocatello, Idaho. July 5, 1958. p. 8. Retrieved April 21, 2019 – via
  19. ^ a b Benthien, Arden (September 4, 1965). "Gap Being Filled In Superhighway". Weekender Magazine. Idaho Free Press. p. 3. Retrieved April 19, 2019 – via
  20. ^ "Interstate Opens Near Boise". Idaho State Journal. Associated Press. December 13, 1968. p. 8. Retrieved April 19, 2019 – via
  21. ^ Benthien, Arden (September 29, 1965). "Nampa-to-Meridian Superhighway Opens". Idaho Free Press. Nampa, Idaho. p. 1. Retrieved April 23, 2019 – via
  22. ^ "Boise West Connector Dedicated at Ceremonies Thursday; New Highway Connector Links Boise, Interstate". The Idaho Statesman. December 13, 1968. p. 1D. Retrieved August 26, 2021 – via
  23. ^ "Mayors Cite Importance Of New Highway Section". Idaho Free Press. Nampa, Idaho. December 21, 1966. p. 1. Retrieved April 23, 2019 – via
  24. ^ Bailey, Margaret (December 2, 1969). "Trucks Roll in Opening Of Bypass". The Idaho Statesman. p. 9A. Retrieved February 11, 2023 – via
  25. ^ "Studying wildlife ecology through road-killed animals". Idaho State Journal. October 31, 2018. Retrieved April 19, 2019.
  26. ^ "Interstate 80N will become Interstate 84 on May Day". Statesman Journal. April 3, 1980. p. B. Retrieved April 21, 2019 – via
  27. ^ Special Committee on U.S. Route Numbering (July 6, 1977). "Route Numbering Committee Agenda" (PDF) (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 485. Retrieved February 12, 2023 – via Wikimedia Commons.
  28. ^ "Interstate signs changed to read I-84". Times-News. Twin Falls, Idaho. April 25, 1980. p. B2. Retrieved April 23, 2019 – via
  29. ^ Williams, Terrell; Garber, Virginia (July 17, 1996). "New Interstate 84 rest area slated for Malad Gorge". Times-News. Twin Falls, Idaho. p. B1. Retrieved April 20, 2019 – via
  30. ^ Kreller, Kathleen (November 14, 2004). "Meridian growth, traffic on a collision course". Idaho Statesman. p. 1.
  31. ^ Sewell, Cynthia (January 11, 2017). "From the archives: ITD cancels I-84 makeover of Nampa-Caldwell section". Idaho Statesman. Retrieved February 12, 2023.
  32. ^ Nance, Jesse (October 31, 2009). "I-84 milestone celebrated". Idaho Press. p. 1.
  33. ^ Sewell, Cynthia (August 2, 2011). "Fourth westbound lane on I-84 between Meridian, Garrity interchanges will open Wednesday". Idaho Statesman.
  34. ^ "Ten Mile Interchange now open". The Idaho Press. May 25, 2011. Retrieved April 19, 2019.
  35. ^ Talerico, Kate (June 23, 2019). "Drivers have wanted this stretch of I-84 widened for a decade. It's finally happening". Idaho Statesman. Retrieved February 12, 2023.
  36. ^ a b I-84 Corridor: Caldwell–Nampa (PDF) (Map). Idaho Transportation Department. December 2021. Retrieved February 12, 2023.
  37. ^ Bamer, Erin (September 2, 2019). "I-84 construction in Nampa to last through next year". The Idaho Press. Retrieved February 12, 2023.
  38. ^ Bamer, Erin (March 28, 2020). "Widening of I-84 continues in Canyon County". The Idaho Press. Retrieved February 12, 2023.
  39. ^ Corbin, Clark (July 13, 2021). "$300M I-84 expansion project will add lanes, replace bridges in Canyon County". The Idaho Press. Retrieved February 12, 2023.
  40. ^ Roberts, Rachel (April 19, 2023). "Update: Weather delays opening of extra lanes on I-84 between Caldwell and Nampa". Idaho Statesman. Retrieved June 21, 2023.
  41. ^ Kennison, Heather (April 27, 2017). "State to spend $36M in new construction in region". Times-News. Twin Falls, Idaho. Retrieved April 20, 2019.
  42. ^ Rumpf, Morgan. "Jerome rest area to permanently close". Retrieved 2019-11-09.
  43. ^ "Cotterell Rest Area wins engineering excellence award". Weekly Mailer. Retrieved 2019-11-09.
  44. ^ ":: Interstate Oasis Program, 9855-9857 [E6-2682] ::". Justia Regulation Tracker. Retrieved 2019-11-09.

External links

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