List of Idaho State Highways

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Interstate 15 markerU.S. Route 20 marker State Highway 200 marker
Highway markers for Interstate 15, U.S. Route 20, and State Highway 200
Highway names
Interstates: Interstate X (I-X)
US Routes: U.S. Route X (US X)
State: Idaho Route X (SH-X)
System links
State Highways in Idaho

The Idaho Transportation Department is responsible for the establishment and classification of a state highway network which includes the interstate highways, U.S. highways, and state routes. These routes are listed below.


Instead of numbering its highways, Idaho had a system of lettered Sampson Trails in the 1920s.[1] They were marked by Charles B. Sampson of Boise at no expense to the state.[2] By the mid-1930s, the state had adopted a more standard system of numbered state highways.[3][4]

The following trails were marked:[1]


I-15.svg Interstate 15 At 200 miles (320 km) in length, it traverses through Pocatello, Blackfoot, and Idaho Falls. I-15 (ID) map.svg
I-84.svg Interstate 84 Crossing through the "heel" of the Idaho "boot", this interstate passes through Boise, near Twin Falls, and other smaller towns. I-84 (ID) map.svg
I-86.svg Interstate 86 Located entirely within Idaho, it stretches from Interstate 84 in Heyburn to Interstate 15 at Pocatello. I-86 (ID) map.svg
I-90.svg Interstate 90 The 73-mile (117 km) segment of interstate highway boasted one of the last traffic lights on the interstate highway system at Wallace. I-90 (ID) map.svg
I-184.svg Interstate 184 This spur connects Interstate 84 travelers to downtown Boise. I-184 (ID) map.svg

U.S. Highways[edit]

US 2.svg US-2
US 10.svg US-10 Replaced by Interstate 90. Interstate 90 Business in Coeur d'Alene, Osburn/Silverton, Post Falls, and Wallace are segments of US-10.
US 12.svg US-12 Runs from the Washington border in Lewiston to the Montana border at Lolo Pass.
US 20.svg US-20 There's a freeway like section in eastern Idaho from Idaho Falls to Chester.
US 26.svg US-26
US 30.svg US-30 mostly Concurrent with Interstate 84 and Interstate 86
US 30N.svg US-30N Renumbered U.S. Route 95 Spur
US 30S.svg US-30S
US 89.svg US-89
US 91.svg US-91
US 93.svg US-93 Runs from Jackpot, Nevada to Lost Trail Pass in Montana. Concurrency with US 26 from Shoshone to Arco.
US 95.svg US-95 Currently being upgraded to a freeway like highway for safety and for a faster and easier way to connect the 2 most populous Metro areas in Idaho.
US 95E.svg US-95E
US 95W.svg US-95W
US 191.svg US-191
US 195.svg US-195
US 287.svg US-287 Section in Idaho renamed Idaho Highway 87
US 410 (1961).svg US-410 Renumbered U.S. Route 12
US 630.svg US-630 Renumbered as U.S. Route 95 Spur in Weiser

State highways[edit]

ID-1.svg SH-1 Connects US-95 to the Canada–United States border at Porthill.
ID-3.svg SH-3 Runs from Nez Perce County north to I-90 in Kootenai County.
ID-4.svg SH-4 A six-mile (10 km) road from Wallace to the ghost towns of Gem and Burke.
ID-5.svg SH-5 A short road from Plummer to St. Maries.
ID-6.svg SH-6 Connects State Highway 3 to the Washington border near Potlatch.
ID-7.svg SH-7 Serves the communities of Orofino and Ahsahka.
ID-8.svg SH-8 Runs from the Washington border at Moscow to Elk River.
ID-9.svg SH-9 Connects State Highway 6 at Princeton to State Highway 8 at Deary.
ID-11.svg SH-11 A road through Weippe and Pierce in Clearwater County.
ID-13.svg SH-13 Runs from Kooskia to downtown Grangeville.
ID-14.svg SH-14 Entirely in Idaho County, it connects Grangeville to Elk City.
ID-16.svg SH-16 A short route from Star to Emmett. A freeway like corridor is planned to extend SH-16 to I-84 West.
ID-19.svg SH-19 A valley road from Caldwell to the Oregon border near Homedale.
ID-21.svg SH-21 Runs from the east end of Boise to Stanley.
ID-22.svg SH-22 A route from Dubois to Butte County, where it joins State Highway 33.
ID-24.svg SH-24 In south-central Idaho from Burley to Shoshone.
ID-25.svg SH-25 Runs near Interstate 84 from Jerome to the Declo area.
ID-27.svg SH-27 Connects the town of Oakley to Burley and Paul.
ID-28.svg SH-28 Runs from Salmon to Interstate 15 near the Continental Divide.
ID-29.svg SH-29 A route from Leadore to the nearby Montana border.
ID-31.svg SH-31 In eastern Idaho from Swan Valley to Victor.
ID-32.svg SH-32 An eastern Idaho road from Ashton to Tetonia.
ID-33.svg SH-33 Runs from Butte County to the Wyoming border.
ID-34.svg SH-34 Diverges from State Highway 36 near Preston, and runs to the Wyoming border.
ID-36.svg SH-36 An east-west road from Ovid through Preston to Interstate 15.
ID-37.svg SH-37 Runs from the Oneida/Power county line north to Interstate 86 at American Falls.
ID-38.svg SH-38 Runs east from Holbrook to Malad City and Interstate 15.
ID-39.svg SH-39 A route from Blackfoot to American Falls.
ID-40.svg SH-40 A very short connector from Downey to Interstate 15.
ID-41.svg SH-41 Runs north from Post Falls to the Washington border (near Newport, Washington).
ID-43.svg SH-43 A short route from US Highway 26 north to Ucon.
ID-44.svg SH-44 Cuts across the Treasure Valley from Interstate 84 to Garden City.
ID-45.svg SH-45 Connects State Highway 78 to downtown Nampa.
ID-46.svg SH-46 Runs south from Camas County to Wendell.
ID-47.svg SH-47 A short highway in Fremont County that ends in Ashton.
ID-48.svg SH-48 A route in eastern Idaho from Roberts to Ririe.
ID-50.svg SH-50 Connects US Highway 30 near Kimberly to State Highway 25.
ID-51.svg SH-51 A rural road from Mountain Home south to the Nevada border.
ID-52.svg SH-52 Runs from Horseshoe Bend to the Oregon border at Payette.
ID-53.svg SH-53 Runs west from Rathdrum to the Washington border.
ID-54.svg SH-54 In northern Idaho between Spirit Lake and Bayview.
ID-55.svg SH-55 Begins at Marsing, runs east to Meridian, and turns north to New Meadows.
ID-57.svg SH-57 A route from Priest River to Nordman.
ID-58.svg SH-58 A short continuation of WA 278 to fully connect US Highway 95 to Rockford, Washington.
ID-60.svg SH-60 Runs from US Highway 95 near Plummer to the Washington border.
ID-61.svg SH-61 A one-mile (1.6 km) continuation of WY 89 near Geneva.
ID-62.svg SH-62 A route from Craigmont to Nezperce in north-central Idaho.
ID-64.svg SH-64 Runs east from Nezperce to Kamiah and US Highway 12.
ID-66.svg SH-66 A one-mile (1.6 km) road from US Highway 95, near Viola, that continues into Washington.
ID-67.svg SH-67 A 9-mile (14.4 km) four-lane highway between Mountain Home and Mountain Home Air Force Base.
ID-69.svg SH-69 A short highway from Kuna to Interstate 84 in Meridian.
ID-71.svg SH-71 Connects Cambridge to the Oregon border near Brownlee Dam.
ID-72.svg SH-72 Connects New Plymouth to nearby State Highway 52.
ID-74.svg SH-74 Starts just south of Twin Falls and ends in the downtown area.
ID-75.svg SH-75 Runs from Shoshone through the Sun Valley area to Challis.
ID-77.svg SH-77 Connects US Highway 30 to Malta.
ID-78.svg SH-78 A rural highway from Marsing to Hammett.
ID-79.svg SH-79 A road from US Highway 93 in Twin Falls north to Jerome.
ID-81.svg SH-81 Runs from Malta to Burley.
ID-87.svg SH-87 Runs from US Highway 20 near Henrys Lake to the Montana border.
ID-97.svg SH-97 A route from Harrison to Interstate 90.
ID-99.svg SH-99 A short highway from Troy to Kendrick.
ID-128.svg SH-128 A road in north Lewiston that runs to the Washington border.
ID-162.svg SH-162 A route from Nezperce to Kamiah.
ID-167.svg SH-167 A road between Grand View and Mountain Home Air Force Base.
ID-200.svg SH-200 Pend Oreille Scenic Byway runs east from Ponderay, ID to the Montana border.

See also[edit]


  1. ^ a b Rand McNally Auto Road Atlas, 1926, accessed via the Broer Map Library
  2. ^ Senate Concurrent Resolution No. 8, "a concurrent permit Charles B. Sampson to extend the marking system of the Sampson Trail..." passed February 16, 1933
  3. ^ H.M. Gousha Company, Western States road map, published by Standard Oil Company of California, 1935
  4. ^ Rand McNally and Company, Road map: Idaho, Mont., Wyo., published by Texaco, 1937

External links[edit]