Interstate Highways of the Idaho State Highway System

Interstate 15 marker

Interstate 184 marker

Interstate 90 Business marker

Typical Interstate highway markers
Interstate Highways highlighted in red
System information
Maintained by ITD
Length611.31 mi[1] (983.81 km)
Formed1956
Highway names
InterstatesInterstate n (I-n)
US HighwaysU.S. Highway n (US-n)
StateIdaho State Highway n (SH-n)
System links
  • Idaho State Highway System

The Interstate Highways in Idaho are the segments of the Dwight D. Eisenhower National System of Interstate and Defense Highways owned and maintained by the Idaho Transportation Department (ITD) in the U.S. state of Idaho. The state has five Interstate Highways that total approximately 611 miles (983 km) in length.[1]

Mainline highways

Number Length (mi)[2] Length (km) Southern or western terminus Northern or eastern terminus Formed Removed Notes
I-15 196.000315.431 I-15 near WoodruffI-15 at Monida Pass 01957-01-011957current  
I-15W 62.850101.147 I-84 / US 30 near DecloI-15 in Chubbuck 01957-01-01195701978-01-011978 Became I-86
I-80N 275.650443.616 I-84 near FruitlandI-84 near Black Pine 01957-01-01195701980-01-011980 Became I-84
I-84 275.650443.616 I-84 near FruitlandI-84 near Black Pine 01980-01-011980current Designated as I-80N until 1980
I-86 62.850101.147 I-84 / US 30 near DecloI-15 in Chubbuck 01978-01-011978current Designated as I-15W until 1978
I-90 73.888118.911 I-90 in State LineI-90 at Lookout Pass 01957-01-011957current  
I-180N 3.6205.826 I-84 / US 30 in BoiseUS 20 / US 26 in Boise 01970-01-01197001979-01-011979 Became I-184
I-184 3.6205.826 I-84 / US 30 in BoiseUS 20 / US 26 in Boise 01979-01-011979current Designated as I-180N until 1979, completed in 1990
  •       Former

Business routes

Number Length (mi)[2] Length (km) Southern or western terminus Northern or eastern terminus Formed Removed Notes
I-15 BL 4.3386.981 I-15/US 91 exit 44 near McCammonI-15/US 30/US 91 exit 47 in McCammon
I-15 BL 1.0001.609 I-15/US 30/US 91 exit 57 in InkomI-15/US 30/US 91 exit 58 in Inkom
I-15 BL 5.5608.948 I-15/US 30/US 91 exit 67 in PocatelloI-15 exit 69 in Pocatello US 30 and US 91 branches off I-15 at its southern end
I-15 BL 4.8027.728 I-15 exit 89 southwest of BlackfootI-15/US 26 exit 93 in Blackfoot I-15 and US 26 begin concurrency at northern end
I-15 BL 7.23011.636 I-15/US 26 exit 116 near Idaho FallsI-15/US 20 Bus. exit 118 in Idaho Falls Concurrent with Us 26 at south end and US 20 Bus. at north end
I-84 BL 12.55720.209 I-84/US 20/US 26/US 30 exit 27 in CaldwellI-84/US 30/SH-55 exit 38 in Nampa
I-84 BL I-84/US 30 exit 49 west of BoiseI-84/US 20/US 26/US 30 exit 54 in Boise Now part of I-184, US 20, and US 26
I-84 BL 5.9859.632 I-84/US 20/US 26/US 30 exit 90 near Mountain HomeI-84/US 26/US 30 exit 99 near Mountain Home
I-84 BL I-84/US 26/US 30/SH-78 exit 112 in HammettI-84/US 26/US 30 exit 114 near Hammett Runs concurrent with SH-78 at west end
I-84 BL 1.4252.293 I-84/US 26/US 30 exit 120 in Glenns FerryI-84/US 26/US 30 exit 121 in Glenns Ferry
I-84 BL 3.5185.662 I-84/US 26/US 30 exit 137 near BlissI-84/US 26 exit 141 in Bliss Runs concurrent with US 30 near whole length. Road continues as US 26 at east end
I-84 BL 6.5610.56 I-84/SH-27 exit 208 near BurleyI-84/US 30/SH-24 near Heyburn Entirely concurrent with SH-27 at west end then US 30 to east end. Road continues as SH-24
I-86 BL 6.47510.421 I-86/US 30/SH-37 exit 36 near NeeleyI-86/US 30/SH-39 exit 40 in American Falls 01972-01-011972current Concurrent with SH-39 toward east end
I-90 BL 5.6409.077 I-90 exit 2 west of Post FallsI-90 exit 6 in Post Falls
I-90 BL 3.8346.170 I-90 exit 11 near Coeur d'AleneI-90 exit 15 in Coeur d'Alene
I-90 BL 1.42.3 I-90 exit 49 near KelloggI-90 exit 51 in Kellogg
I-90 BS 3.9666.383 I-90 exit 57 in OsburnE. Mullan Ave. in downtown Osburn Originally a business loop that ran from exit 57 to exit 60 to Silverton via Silver Valley Road. Split into two separate spurs
I-90 BS 0.120.19 I-90 exit 60 in SilvertonSilver Valley Rd south of Silverton Part of original loop that once ran from I-90 exit 57 in Osburn to exit 60 in Silverton via Silver Valley road. Split into two separate spurs
I-90 BL 1.2432.000 I-90 exit 61 near WallaceI-90 exit 62 in Wallace Originally part of I-90 that contained a traffic signal before entering Wallace. Became I-90BL when I-90 was rerouted north as a full freeway
I-90 BL 1.0001.609 I-90 exit 68 in MullanI-90 exit 69 near Mullan
  •       Former

See also

References

  1. 1 2 "National Highway Freight Network Map and Tables for Idaho". Federal Highway Administration. 2015. Retrieved December 11, 2022.
  2. 1 2 "Milepoint Logs". Idaho Transportation Department. Retrieved February 15, 2017.
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